Questions for Exam Practice
One Day at a Time A not-so-overwhelming book to practice Chemistry Regents exam questions 30 days of questions sets Answers given to all questions Clean Clear Easy-to-understand explanations of correct answers 2 full Regents exams Track Your Progress
Effiong Eyo Scholastic Publishing
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Format of this book: This book contains sets of Chemistry Regents exam questions organized into days. There are a total of 30 days of questions review. On all ODD days, students will practice only Multiple Choice exam questions. The number of multiple choice questions increases from 10 to 15 to 20 on days 1 – 25. The Two regents exams offer students the opportunity to practice (on days 27 and 29) two sets of 50 multiple choice questions. On all EVEN days, students will practice only Constructed Response exam questions. The number of Constructed Response questions stays constant at 10 from days 2 – 26. The two Regents exams offer students the opportunity to practice (on days 28 and 30) two sets of 30 to 34 Constructed Response questions . Answers: Answers are given to all exam questions in this book. Explanations: Clean, Clear, and Easy-to-understand explanations are given to all questions on Days 1 – 26. The Goal of this book: The format of this book is intended to allow students to:
. Practice more chemistry Regents exam questions than with any other book . Build up confidence in exam taking
. Build up knowledge of testable chemistry concepts . Track their progress as the Regents exam day approaches . Be better prepared for the chemistry Regents exam
. Do ALL of the above without being too overwhelm
Table of Contents Multiple Choice Questions Sets Day
Questions Answers and Explanations
Day Questions
Answers and Explanations
1
pg 1 - 2
pg 4
17 pg 81-83
pg 84-86
3
pg 9-10
pg 12
19 pg 93-95
pg 96-97
5
pg 17-18
pg 20
21 pg 105-108 pg 110-112
7
pg 25-26
pg 28
23 pg 119-122 pg 124-126
9
pg 35-37
pg 38-39
25 pg 133-137 pg 138-140
11
pg 47-49
pg 50-51
27 pg 147-157 pg 158
13
pg 57-59
pg 60-61
29 pg 179-188 pg 190
15
pg 69-72
pg 74-75
Constructed Response Questions Sets Day
Questions
Answers
Day Questions
Answers
2
pg 5-6
pg 8
18
pg 87-89
pg 90-91
4
pg 13-15
pg 16
20
pg 99-101
pg 102-103
6
pg 21-22
pg 24
22
pg 113-115 pg 116-117
8
pg 29-30
pg 32-33
24
pg 127-129 pg 130-140
10
pg 41-42
pg 44-45
26
pg 141-143 pg 144-145
12
pg 53-55
pg 56
28
pg 159-167 pg 174-177
14
pg 63-65
pg 66-67
30
pg 191-199 pg 207-211
16
pg 77-79
pg 80
Track Your Progress
Pg 213 - 214
Day 1: Start:
10 Multiple choice questions
Answer all 10 questions on this day before stopping.
1. Which subatomic particle is negatively charged? (1) electron (3) positron (2) neutron (4) proton 2. An element that is malleable and is a good conductor of heat and electricity could have an atomic number of (1) 16 (3) 29 (2) 18 (4) 35 3. The chemical bonding in sodium phosphate, Na3PO4, is classified as (1) ionic, only (2) metallic, only (3) both covalent and ionic (4) both covalent and metallic 4. At 65oC, which compound has a vapor pressure of 58 kilopascals? (1) ethanoic acid (3) propane (2) ethanol (4) water 5. Which compound is a saturated hydrocarbon? (1) propanal (3) propene (2) propane (4) propyne 6. A beta particle may be spontaneously emitted from (1) a ground-state atom (2) a stable nucleus (3) an excited electron (4) an unstable nucleus 7. The compound C2H4 and C4H8 have the same (1) freezing point at standard temperature (2) boiling point at standard temperature (3) molecular formula (4) empirical formula
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Day 2:
10 Constructed Response questions
Start:
Answer all 10 questions on this day before stopping.
Base your answers to questions 1 through 3 on the information below.
Two isotopes of potassium are K-37 and K-42. 1. What is the total number of neutrons in the nucleus of a K-37 atom? [1] 2. How many valance electrons are in an atom of K-42 in the ground state? [1] 3. Explain, in terms of subatomic particles, why K-37 and K-42 are isotopes of potassium? [1]
Base your answers to questions 4 through 6 on the potential energy diagram below.
4. What is the heat of reaction for the forward reaction? [1]
____ KJ
5. What is the activation energy for the forward reaction with the catalyst? [1] _____KJ 6. Explain, in terms of the function of a catalyst, why the curves on the potential energy diagram for the catalyzed and the uncatalyzed reactions are different? [1]
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7
Day 3: Start:
10 Multiple Choice questions
Answer all 10 questions on this day before stopping.
1. Which element has the greatest density at STP? (1) barium (3) magnesium (2) beryllium (4) radium 2. A 1.0-mole sample of krypton gas has a mass of (1) 19 g (3) 39 g (2) 36 g (4) 84 g 3. Standard pressure is equal to (1) 1 atm (2) 1 kPa
(3) 273 atm (4) 273 kPa
4. According to the kinetic molecular theory, the molecules of an ideal gas (1) have a strong attraction for each other (2) have a significant volume (3) move in random, constant, straight-line motion (4) are closely packed in a regular repeating pattern 5. The isomers butane and methyl propane differ in their (1) molecular formulas (2) structural formula (3) total number of atoms per molecule (4) total number of bonds per molecule 6. In the formula X2O , the symbol X could represent an element in Group (1) 1 (3) 15 (2) 2 (4) 18 7. Molarity is defined as (1) moles of solutes per kilogram of solvent (2) moles of solute per liter of solution (3) mass of a solution (4) volume of solvent
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Day 4: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
Base your answers to questions 1 and 2 on the information below.
Archimedes (287 – 212 BC), a Greek inventor and mathematician, made several discoveries important to science today. According to a legend, Hiero, the king of Syracuse, commanded Archimedes to find out if the royal crown was made of gold, only. The king suspected that the grown consisted of a mixture of gold, tin, and copper. Archimedes measured the mass of the crown and the total amount of water displaced by the crown when it was submerged. He repeated the procedure using individual samples, one gold, one tin, and one copper. Archimedes was unable to determine that the crown was not made entirely of gold without damaging it. 1. Identify one physical property that Archimedes used in his comparison of the metal samples. [1]
2. Determine the volume of a 75-gram sample of gold at STP. [1]
Base your answers to questions 3 and 4 on the information below.
Many esters have distinctive odors, which lead to their widespread use as artificial flavorings and fragrances. For example, methyl butanoate has an odor like pineapple and ethyl methanoate has an odor like raspberry. 3. In the space below, draw a structural formula for the ester that has an odor like pineapple. [1]
4. What is the chemical name for an alcohol that reacts with methanoic acid to produce the ester that has an odor like raspberry? [1]
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13
Day 4:
continue.
Base your answers to question 8 through 10 on the information below.
A beaker contains 100.0 millimeters of a dilute aqueous solution of ethanoic acid at equilibrium. The equation below represents this system. HC2H3O2(aq) < === > H+(aq) + C2H3O2 -(aq) 8. Compare the rate of the forward reaction to the rate of the reverse reaction for this system. [1]
9. Describe what happens to the concentration of H+(aq) when 10 drops of concentrated HC2H3O2(aq) are added to this system. [1]
10. In the space below, draw a structural formula for ethanoic acid. [1]
Day 4 Stop. Correct your answers and note how many correct Points
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15
Day 5: Start:
10 Multiple Choice questions
Answer all 10 questions on this day before stopping.
1. What is the mass number of a carbon atom that contains six protons, eight neutrons, and six electrons? (1) 6 (3) 14 (2) 8 (4) 20 2. An atom in the ground state has a stable valance electron configuration. This atom could be an atom of (1) Al (3) Na (2) Cl (4) Ne 3. Which equation represents an exothermic reaction at 298 K? (1) N2(g) + O2(g) --------- > 2NO)g) (2) C(s) + O2(g) ---------- > CO2(g) HO
2 (3) KNO3(s) --------> K+(aq)
HO
2 (4) NH4Cl(s) -------> NH4+(aq) + Cl-(aq)
4. Compared to the freezing and boiling point of water at 1 atmosphere, a solution of salt and water at 1 atmosphere has a (1) lower freezing point and a higher boiling point (2) lower freezing point and a lower boiling point (3) higher freezing point and a lower boiling point (4) higher freezing point and a higher boiling point 5. Which word equation represents a neutralization reaction? (1) base + acid ---- > salt + water (2) base + salt ---- > water + acid (3) salt + acid ---- > base + water (4) salt + water ---- > acid + base 6. Which particle has the greatest mass? (1) an alpha particle (2) a beta particle
(3) a neutron (4) a positron
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Day 6: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
1. Identify one ion from Table F that can combine with Pb2+(aq) to produce an insoluble compound. [1] 2. Describe one appropriate laboratory test that can be used to determine the malleability of a solid sample of an element at room temperature. [1]
3. State two methods to increase the rate of a chemical reaction and explain, in terms of particle behavior, how each method increases the reaction rate. [2]
Base your answers to questions 4 through 5 on the graph below, which represents the cooling of a substance starting at a temperature above its boiling point.
4. What is the boiling point of this substance? [1]
5. Which segment of the graph represents the gas phase, only? [1]
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23
Day 7: Start:
10 Multiple Choice questions
Answer all 10 questions on this day before stopping.
1. Which conclusion was a direct result of the gold foil experiment? (1) An atom is mostly empty space with a dense positively charged nucleus (2) An atom is composed of at least three types of subatomic particles (3) An electron has a positive charge and is located inside the nucleus (4) An electron has properties of both waves and particles 2. Which atom has an atom with the greatest attraction in a chemical bond? (1) As (3) N (2) Bi (4) P 3. Which formula represents a polar molecule? (1) Br2 (3) CH4 (2) CO2 (4) NH3 4. In which sample is the average kinetic energy of particles greatest? (1) 10. mL of HCl(aq) at 25oC (3) 10. mL of H2O(l) at 35oC o (2) 15. mL of HCl(aq) at 20 C (4) 15. mL of H2O(l) at 30oC 5. System in nature tend to undergo changes toward (1) lower energy and less disorder (2) lower energy and more disorder (3) higher energy and less disorder (4) higher energy and more disorder 6. Which half-reaction equation represents the reduction of a potassium ion? (1) K+ + e- ---- > K (3) K+ --- > K + e+ (2) K + e- ----- > K (4) K ---- > K+ + e-
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27
Day 8: Start:
10 Constructed Response Questions Answer all 10 questions on this day before stopping.
Base your answers to questions 1 and 2 on the information below. A light bulb contains argon gas at a temperature of 295 K and a pressure of 75 kilopascals. The light bulb is switch on, and after 30 minutes its temperature is 418 K. Assume the volume of the light bulb remains constant. 1. In the space below show a correct numerical setup for calculating the pressure of the gas inside the light bulb at 418 K. Assume the volume of the light bulb remains constant. [1]
2. What Celsius temperature is equal to 418 K ? [1]
___oC
Base your answers to questions 3 through 5 on the diagram of a voltaic cell and the balance ionic equation below.
3. What is the total number of moles of electrons needed to completely reduce 6.0 moles of Ni2+(aq) ions? [1] ____ mol 4. Identify one metal from Reference Table J that is more easily reduced than Mg(s) . [1]
5. Explain the function of salt bridge in the voltaic cell. [1]
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Day 8: 7) +5
Answers and Explanations: continue
Recall: sum of charges in a compound must equal zero (0) Note: In KClO3 K = +1
1(+1) = +1 (total + so far)
O = -2 3 (-2) = -6 total – in formula Determine charge of Cl : Must be
+ 5 for charges to equal 0
8) Alpha decay or natural transmutation Note: Decay mode (alpha) for C-14 is listed on Table N Recall: alpha decay is a type of natural transmutation 9) 28650 y
Note: This is a half-life problem that should be set up and solve using the fraction remaining equation Recall: Fraction Remaining equation is on Table T Use fraction 1/32 to determine # of half-life periods (n) 1/32 = 1/ n Fraction Remaining = n=5 2 Use equation below to determine length of time Length of Time = half-life x n = 5730 x 5 = 28650 y Note: Half-life of C-14 (5730 yrs) is given on Table N
10) C-13 is different from C-12 in that C-13 has a different number (more) neutrons. Note: C-12 and C-13 are isotopes Recall: isotopes are different because of the different numbers of neutron
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33
Day 9: Start:
10 Multiple Choice questions
Answer all 10 questions on this day before stopping.
1. In the wave-mechanical model of the atom, orbitals are regions of the most probable locations of (1) protons (3) neutrons (2) positrons (4) electrons 2. As the elements of Group 17 are considered in order of increasing atomic number, there is an increase in (1) atomic radius (2) electronegativity (3) first ionization energy (4) number of electrons in the first shell 3. What is the chemical formula for iron (III) oxide? (1) FeO (3) Fe3O (2) Fe2O3 (4) Fe3O2
4. Given a formula for oxygen:
..
..
O ..= O .. What is the total number of electrons shared between the atoms represented in this formula? (1) 1 (3) 8 (2) 2 (4) 4 5. What is the IUPAC name of the organic compound that has the formula shown below? H I H–C–H H H H H I I I I H–C–C–C–C–C–H I I I I I H H H H H (1) 1,1-dimethylbutane (2) 2-methylpentane
(3) hexane (4) 4-methylpentane
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35
Day 9:
continue.
9. A sample of a gas occupies a volume of 50. millimeters in a cylinder with a movable piston. The pressure of the sample is 0.90 atmosphere and the temperature is 298 K. What is the volume of the sample at STP? (1) 41 mL (3) 51 mL (2) 49 mL (4) 55 mL 10. Which general formula represents the compound CH3CH2CCH? (1) CnHn (3) CnH2n-2 (2) CnH2n (4) CnH2n+2
Day 9 Stop. Correct your answers and note how many correct Points
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37
Day 9:
Answers and Explanations: continue
7) 3 Note: Part of the answer to this questions requires using Table G. According to Table G In 100g H2O at 25oC: 35g of KCl forms a saturated solution In 50g H2O at 25oC : 17.5 g of KCl will be a saturated solution (Half amount of H2O)
(Half the grams of KCl)
Note: only 5 g of KCl is in solution in the question Recall: a solution (which is always a homogeneous mixture) containing less (5g KCl) than the saturated amount (17.5 g) is unsaturated 8) 1 Note from the graph: melting occurs between the 2nd and 5th minutes ( a total of 3 minutes) at 50oC 9) 1 Note: This is a Gas law problem: Use Combined Gas Law equation on Table T to setup and solve for the new volume P1V1 P2V2 T1 = T2 (.9)(50) = 1(X) Setup 298 273 298 X = (.9) (50) (273 cross-multiply to get X = 41.2 mL calculated result for V2
10) 3 Note the following about the formula: CH3CH2CCH (C4H6 ) there are 4C 6 H (the number of H is twice the number of C minus 2) Relate: This formula fits general formula CnH2n-2 (Listed on Table Q for alkynes)
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39
Day 10: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
1. What is the oxidation number of nitrogen in NO(g) ? [1] 2. Write an electron configuration for an atom of aluminum-27 in an excited state. [1]
3. What color is bromcresol green after it is added to a sample of NaOH(aq)? [1]
4. Because tap water is highly acidic, water pipes made of iron erode over time, as shown by the balanced ionic equation below: 2Fe +
6H+ ------ > 2Fe3+ +
3H2
Explain, in terms of chemical reactivity, why copper pipes are less likely to corrode than iron pipes. [1]
Base your answers to questions 5through 6 on the information below.
Given the balance equation for an organic reaction between butane and chlorine that takes place at 300oC and 101.3 kilopascals: C4H10 + Cl2 ----- > C4H9Cl + HCl 5. Identify the type of organic reaction shown. [1] 6. In the space below, draw the structural formula for the organic product. [1]
7. Explain, in terms of collision theory, why the rate of the reaction would decrease if the temperature of the reaction mixture was lowered to 200.oC with pressure remaining unchanged. [1]
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Day 10:
Answers and Explanations: continue
7. Rate of the reaction will decrease when temperature is decreased because particles will collide less frequently due to a decrease in their average kinetic energy. 8.
9.
10. As atomic number increases, boiling point increases. Note: Your answer may vary based on your graph
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45
Day 11: Start:
15 Multiple Choice questions
Answer all 15 questions on this day before stopping.
1. Which particle has a mass approximately the same as the mass of a proton? (1) an alpha particle (3) a neutron (2) a beta particle (4) a positron 2. The most common isotope of chromium has a mass of 52. Which notation represents a different isotope of chromium? 24 Cr (1) 52 Cr (3) 52 24 (2)
54 Cr 24
(4) 24 Cr 54
3. Which substance can be broken down by chemical means? (1) CO (3) Ca (2) Ce (4) Cu 4. The bonds in BaO are best described as (1) covalent, because valance electrons are shared (2) covalent, because valance electrons are transferred (3) ionic, because valance electrons are shared (4) ionic, because valance electrons are transferred 5. The net energy released or absorbed during a reversible chemical reaction is equal to (1) the activation energy of the endothermic reaction (2) the activation energy of the exothermic reaction (3) the difference in the potential energy of products and the potential energy of the reactants (4) The sum of the potential energy of the products and the potential energy of the reactants 6. Which class of organic compounds has a molecule that contain nitrogen atom? (1) alcohol (3) ether (2) amine (4) ketone
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47
Day 11:
continue.
12. The diagram below represents the nucleus of an atom. 9p 11 n
What are the atomic number and the mass number of this atom? (1) The atomic number is 9 and the mass number is 19 (2) The atomic number is 9 and the mass number is 20 (3) The atomic number is 11 and the mass number is 19 (4) The atomic number is 11 and the mass number is 20 13. Which list of elements consist of metalloids? (1) B, Al, Ga (3) O, S, Se (2) C, N, P (4) Si, Ge, As 14. Which volume of 0.10 M NaOH(aq) exactly neutralizes 15.0 millimeters of 0.20 M HNO3 (aq) ? (1) 1.5 mL (3) 3.0 mL (2) 7.5 mL (4) 30. mL 15. Which fraction of an original 20.00-gram sample of nitrogen-16 remains unchanged after 36.0 seconds? (1) 1/5 (3) 1/16 1 (2) /8 (4) 1/32
Day 11 Stop. Correct your answers and note how many correct Points
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49
Day 11:
Answers and Explanations. continue
11) 2 Note: according to the equation, NH3 accepts a H+ to become NH4+ NH3
+
H2O ------- > NH4+ + OH-
+
H+(proton)
H (proton) acceptor
donor
12) 2 Recall: Atomic number (9) = number of protons (9p) Recall: Mass number (20) = Protons (9)
+ neutrons (11)
13) 4 Use Periodic Table to note elements that are metalloids 14) 4 Note: This is a titration problem Use titration equation on Table T to setup and solve for volume MA VA = MB VB Setup
(0.20)(15.0) = (0.10) (X)
Solve
30 mL
=
X
15) 4 Note: This is a half-life problem that can be solved in two steps. First: Calculate number of half-life periods (n) from times. n=
length of time (T)
=
half- life (t)
36 7.2
= 5
Note: half-life of N-16 is on Table N Second: Calculate Fraction remaining using Table T equation 1 Fraction remaining =
2n
1 =
2 x2 x2 x2 x2
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1 =
32
51
Day 12: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
Base your answers to questions 1 through 3 on the information below.
The particle diagrams below represents the reaction between two nonmetals, A2 and Q2. Key = Atom of element A = Atom of element Q reactants
products
1. Using the symbols A and Q, write the chemical formula of the product. [1]
2. Identify the type of chemical bond between an atom of element A and an atom of element Q. [1]
3. Compare the total mass of the reactants to the total mass of the product. [1]
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53
6. On the grid below, plot the data from the data table for frequency and energy. Circle and connect the points, including the point (0,0) that has already been plotted and circled for you. [1]
7. A spectral line in the infrared region of the spectrum of hydrogen has a frequency of 2.3 x 1014 hertz. Using your graph, estimate the energy associated with this spectral line. [1] _________ x 10-19 8. Explain, in terms of subatomic particles and energy states, why light is emitted by the hydrogen gas. [1]
9. Identify one condition not mentioned in the passage, under which hydrogen gas behaves most like an ideal gas. [1]
Day 12 Stop. Correct your answers and note how many correct Points Copyright © 2011 E3 Scholastic Publishing. All Rights Reserved
55
Day 13: Start:
15 Multiple Choice questions
Answer all 15 questions on this day before stopping.
1. Which quantity identifies an element? (1) atomic number (2) mass number (3) total number of neutrons in an atom of the element (4) total number of valance electrons in an atom of the element 2. Which element has the greatest density? (1) calcium (3) chlorine (2) carbon (4) copper 3. Which equation shows conservation of atoms? (1) H2 + O2 ----- > H2O (2) H2 + O2 ------ > 2H2O (3) 2H2 + O2 ---- > 2H2O (4) 2H2 + 2O2 ---- > 2H2O 4. A solid substance is an excellent conductor of electricity. The chemical bonds in this substance are mostly (1) ionic, because valance electrons are shared between atoms (2) ionic, because the valance electrons are mobile (3) metallic, because the valance electrons are stationary (4) metallic, because the valance electrons are mobile 5. Which barium salt is insoluble in water? (1) BaCO3 (3) Ba(ClO4)2 (2) BaCl2 (4) Ba(NO3)2 6. Which substance is an Arrhenius acid? (1) Ba(OH)2 (3) H3PO4 (2) CH3COOCH3 (4) NaCl 7. Which energy conversion occurs in a voltaic cell? (1) chemical energy to electrical energy (2) chemical energy to nuclear energy (3) electrical energy to chemical energy (4) nuclear energy to electrical energy
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Day 13:
continue.
14. The potential energy diagram for a chemical reaction is shown below.
Each interval on the axis labeled “Potential Energy (KJ)” represents 40 kilojoules. What is the heat of reaction? (1) -120 KJ (3) +40 KJ (2) -40 KJ (4) +160 KJ 15. Given the balanced equation representing a nuclear reaction: 235
1
92
0
U + n ----- >
142 56
Ba +
91 36
Which particle is represented by X? 0 (1) e -1
Kr + 3X + energy 4
(3) He 2
1 1
1 0
(2) H
(4) n
Day 13 Stop. Correct your answers and note how many correct Points
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59
Day 13:
Answers and Explanations continue.
10) 1 Recall: Brittleness and low conductivity describe nonmetallic solids. Relate: Sulfur is a nonmetal. 11) 4 Recall: A decrease in pH (becomes more acidic) is a result of an increase in hydronium (H3O+) or hydrogen ion (H+) concentration . Recall: 10 fold increase in H3O+ = 1 value decrease in pH 100 fold increase in H3O+ = 2 values decrease in pH Correct choice (pH 3 to pH 1 ) is a 2 value decrease 12) 3 Determine greatest common factor and reduce the subscripts by that factor. Note: C6H12Cl2O2 has GCF of 2, and can be reduced to C3H2ClO 13) 1 Note: C3H8 fits general formula for alkanes,CnH2n+6 (Table Q) Note: CH4 is also an alkane, therefore, same homologous series 14) 3 Recall: Heat of reaction (∆H) = Hproduct – Hreactant Note from diagram: Hproduct (120 KJ) and Hreactant (80 KJ). Calculate: Heat of reaction (∆H) = 120 KJ – 80 KJ = +40 KJ 15) 4 Note: The equation represent fission reaction Recall: neutrons ( 1 n ) are also released during fission process. 0
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61
Day 14: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
Base your answers to questions 1 though 3 on the data table below.
Formulas and Boiling Points of Selected Alkanes. Name
Formulas
Boiling Point at 1 ATM (oC)
methane
CH4
-162
ethane
C2H6
-89
propane
C3H8
-42
butane
C4H10
-0.5
pentane
C5H12
36
1. In the space below, draw a structural formula for butane. [1]
2. At standard pressure and 298 K, which alkane is a liquid? [1]
3. What is the boiling point of propane at 1 atmosphere, in Kelvins? [1]
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63
Day 14:
continue.
Base your answers to questions 9 and 10 on the information below.
A 4.86 gram sample of calcium reacted completely with oxygen to form 6.80 grams of calcium oxide. This reaction is represented by the balanced equation below. 2 Ca(s)
+ O2(g) ----- >
2CaO(s)
9. Determine the total mass of oxygen that reacted. [1]
10. Explain, in terms of electrons, why the radius of a calcium ion is smaller than the radius of a calcium atom. [1]
Day 14 Stop. Correct your answers and note how many correct Points
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65
Day 14:
continue
Answers and Explanations:
7) No change in solubility Recall: Pressure change has no effect on solubility of a solid such as KNO3(s) 8) 60 grams Use Table G: saturation amount of KNO3 at 15oC = 30g Calculate amount that settle to bottom = Grams KNO3 in solution – saturated grams at 15oC = 90 g – 30 g = 60g 9) 1.94 g
Recall: Total Mass of Reactants = Total Mass of Products Ca +
O2
4.86 g + 1.94 g
------ > =
2 CaO 6.80 g
10) Radius of a calcium ion ( Ca2+) is smaller than the radius of a calcium atom (Ca ) because a calcium ion has 2 less electrons (or 1 less electron shell) than Ca atom Recall: Ca forms a Ca2+ ion (See Periodic Table). Recall: an atom becomes a positive ion by losing electrons
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67
Day 15: Start:
15 Multiple Choice questions
Answer all 15 questions on this day before stopping.
1. Which statement describes the relative energy of the electrons in the shell of a calcium atom? (1) An electron in the first shell has more energy than an electron in the second shell (2 An electron in the first shell has the same amount of energy as an electron in the second shell (3) An electron in the third shell has more energy than an electron in the second shell (4) An electron in the third shell has less energy than an electron in the second shell 2. Which Group 14 element is a metalloid? (1) tin (3) lead (2) silicon (4) carbon 3. Which formula represents a molecular compound? (1) Kr (3) N2O4 (2) LiOH (4) NaI 4. A reaction is most likely to occur when reactant particle collide with (1) proper energy, only (2) proper orientation, only (3 both proper energy and proper orientation (4) neither proper energy nor proper orientation 5. Which element is present in every organic compound? (1) carbon (3) nitrogen (2) fluorine (4) oxygen 6. What is the total number of valance electrons in an atom of germanium in the ground state? (1) 8 (3) 14 (2) 2 (4) 4
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69
Day 15:
continue.
12. What is the percent composition by mass of hydrogen in NH4HCO3 (gram-formula mass = 79 grams per mole) (1) 5.1 % (3) 10. % (2) 6.3 % (4) 50. %
13. Which particle model diagram represents only one compound composed of elements X and Z?
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73
Day 15: 9) 1
Answers and Explanations: continue
Recall: single replacement, decomposition and synthesis reactions are all considered redox reactions. Note: Choice 1 equation is a synthesis reactions. or Recall: a reaction equation is a redox if there is a change of oxidation numbers (lost and gained of electrons) Note: Both P and Cl go through changes in oxidation numbers
10) 2 Recall : number of electron = number of protons (Atomic #) Note: numbers in configuration are number of electrons Sum of numbers in the configuration 2 – 8 – 18 – 32 – 18 – 1 = 79 = number of protons 11) 2 Recall: compounds containing both ionic and covalent bonds likely contain a polyatomic ion or have three or more elements Note: Sodium nitrate (NaNO3) contains a polyatomic ion (NO3). It also contains three different elements 12) 2
Note: Percent composition equation is on Table T total mass of 5 H %H = x 100 formula mass 5 %H = x 100 = 6.1 % 79 13) 1 Recall: a diagram of a compound must show the two different atoms touching (bonding) All units in the diagram must be identical. 14) 1 Temperature: Least entropy must be lowest temp. (266 K) Phase: Lowest entropy must be a solid. Br2(s) 15) 1 Note: this is a half-life problem that can be solved in two steps. First determine number of half-life period from masses. 25 g---> 12.5 ----> 6.25 ---- > 3.125 g (3 arrows = 3 periods) Second: use equation below to determine half-life Length of time 3.9 x 109 Half-life = = = 1.3 x 109 y half-life periods 3
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75
Day 16: Start:
10 Constructed Response Questions Answer all 10 questions on this day before stopping.
Base your answers to questions 1 through 3 on the information below.
A 100.0-gram sample of NaCl(s) has an initial temperature of 0oC. A chemist measures the temperature of the sample as it is heated. Heat is not added at a constant rate. The heating curve for the sample is shown below.
1. Determine the temperature range over which the entire NaCl sample is a liquid. [1] 2. Identify one line segment on the curve where the average kinetic energy of the particles of the NaCl sample is changing. [1]
3. Identify one line segment on the curve where the NaCl sample is in a single phase and capable of conducting electricity. [1]
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77
Day 16:
continue.
Base your answers to questions 7 through 10 on the information below.
When a person perspires (sweats), the body loses many sodium ions and potassium ions. The evaporation of sweat cools the skin. After a strenuous workout, people often quench their thirst with sport drinks that contain NaCl and KCl. A single 250.0 grams serving of one sport drink contains 0.055 gram of sodium ions. 7. In the space below, show a numerical setup for calculating the concentration of sodium ions in this sport drinks, expressed as percent by mass. [1]
8. Describe the transfer of energy between skin and the surroundings as a person perspires and the sweat evaporates. [1]
9. State why the salt in sport drinks are classified as electrolytes. [1]
10. In the space in your answer booklet, draw a Lewis electron-dot diagram for one of the positive ions lost by the body as a person perspires. [1]
Day 16 Stop. Correct your answers and note how many correct Points Copyright © 2011 E3 Scholastic Publishing. All Rights Reserved
79
Day 17: Start:
15 Multiple Choice questions
Answer all 15 questions on this day before stopping.
1. An atom of an element forms a 2+ ion. In which Group on the Periodic Table could this element be located? (1) 1 (3) 13 (2) 2 (4) 17 2. During all chemical reactions, mass, energy, and charge are (1) absorbed (3) formed (2) conserved (4) released 3. Samples of four Group 15 elements, antimony, arsenic, bismuth, and phosphorus, are in the gaseous phase. An atom in the ground state of which element requires the least amount of energy to remove its most loosely held electron? (1) As (3) P (2) Bi (4) Sb 4. An atom of an element has a total of 12 electrons. An ion of the same element has a a total of 10 electrons. Which statement describes the charge and radius of the ion? (1) The ion is positively charged and its radius is smaller than the radius of the atom (2) The ion is positively charged and its radius is larger than the radius of the atom (3) The ion is negatively charged and its radius is smaller than the radius of the atom (4) The ion is negatively charged and its radius is larger than the radius of the atom 5. At STP, which 2.0 gram sample of matter uniformly fills a 340-millimeters closed container? (1) Br2(l) (3) KCl(aq (2) Fe(NO3)2(s) (4) Xe(g) 6. At standard pressure, which element has a freezing point below standard temperature? (1) In (3) Hf (2) Ir (4) Hg
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81
Day 17:
continue.
13. The table below indicates the stability of six nuclides. Stability of Six Nuclide Nuclide Stability C-12
stable
C-14
unstable
N-14
stable
N-16
unstable
O-16
stable
O-19
unstable
All atoms of the unstable nuclide listed in this table have (1) an odd number of neutrons (2) an odd number of protons (3) more neutrons than protons (4) more protons than neutrons 14. What is the oxidation number of sulfur in Na2S2O3? (1) -1 (3) +6 (2) +2 (4) +4 15. Which two compounds have the same molecular formula but different chemical and physical properties? (1) CH3CH2Cl and CH3CH2Br (2) CH3CHCH2 and CH3CH2CH3 (3) CH3CHO and CH3COOCH3 (4) CH3CH2OH and CH3OCH3
Day 17 Stop. Correct your answers and note how many correct Points
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83
Day 17: 10. 1
Answers and Explanations: continue
Note: This is parts per million concentration problem Use parts per million equation (Table T) to setup and solve ppm =
Grams of solute
x
1 000 000
Grams of solution ppm x grams of solution Grams of solute = Grams of solute =
1 000 000 5
x 1000
= 0.005 g
1 000 000 11) 2
Note: An indicator (Table M) is good for distinguishing between two solutions of different pH if the indicator will change different colors in the two solution. Note: According to pH range for bromcresol green (Table M) In a solution with pH 3.5, bromcrsol green will be yellow. In a solution with pH 5.5, bromcresol green will be blue.
12) 3
Recall: a correct reduction equation must show : electrons (e-) lost to the left of arrow and sum of charges must be equal on both sides Note: Mn4+ + e- ---- > Mn3+ is a correct reduction equation because e- is left of arrow and sum of charges are equal (+3) on both sides.
13) 3
Note: This choice is the only true information for all the unstable nuclei: They each have more neutrons (mass # - atomic #) than protons (atomic #) Note: unstable nuclei mass # = protons (atomic #) + neutrons C-14 14 6 8 N-16 16 7 9 O-19 19 8 11
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85
Day 18: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
1. Describe one chemical property of Group 1 metals that results from the atoms of each metal having only one valance electrons. [1]
2. Given the balance equation representing a reaction: N2(g) + O2(g)
+ 182.6 KJ --- > 2NO (g)
Potential Energy
On the labeled axes below, draw a potential energy diagram for this reaction . [1]
Reaction Coordinate
3. Write one electron configuration for an atom of silicon in an excited state. [1]
4. Write the empirical formula for the compound C8H18.
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[1]
87
Day 18:
continue.
Base your answers to questions 8 through 10 on the information below.
Naturally Occurring Isotopes of Sulfur. Isotopes
Atomic Mass (atomic mass unit, u)
Natural Abundance (%)
32S
31.97
94.93
33S
32.97
0.76
34S
33.97
4.29
36S
35.97
0.02
8. State, in terms of the number of subatomic particles, one similarity and one difference between the atoms of these isotopes of sulfur. [1]
9. In the space below, draw a Lewis electron-dot diagram for an atom of sulfur-33. [1]
10. In the space below, show a correct numerical setup for calculating the atomic mass of sulfur. [1]
Day 18 Stop. Correct your answers and note how many correct Points Copyright © 2011 E3 Scholastic Publishing. All Rights Reserved
89
Day 18: 7) 915 J
Answers and Explanations: continue
Note: This is a heat calculation problem Recall: Heat equations are on Table T Use heat of fusion equation: q = m Hf Setup and solve: Heat (q) = (7.5)(122) = 915 J
8) Similarity They all have same number of protons Difference: They have different number of neutrons. Recall: Isotope is defined as atoms of the same element with same number of protons but different number of neutrons
9)
Recall: A Lewis electron-dot structure must show the symbol of the atom ( S) and dots equal to the number of its valance electrons (6). Recall: Number of valance electrons (6) is the last number in a configuration ( 2 – 8 – 6) See Periodic Table.
10) (.9493 x 32) + (.0076 x 33) + (.0429 x 34) + (.0002 x 36) Note: Setup may vary slightly Note: Setup must show the addition of all the products of ( decimal of each percent x the mass #)
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91
Day 19: Start:
15 Multiple Choice questions
Answer all 15 questions on this day before stopping.
1. An atom in the ground state has seven valance electrons. The atom could be an atom of which element? (1) calcium (3) oxygen (2) fluorine (4) sodium 2. Which statement identifies the element arsenic? (1) Arsenic has atomic number of 33. (2) Arsenic has a melting point of 84 K. (3) An atom of arsenic in the ground state has eight valance electrons. (4) An atom of arsenic in the ground state has a radius of 146 pm.. 3. What is the number of electrons in an atom of potassium? (1) 18 (3) 20 (2) 19 (4) 39 4. Which statement describes a chemical property of hydrogen gas? (1) Hydrogen gas burns in air (2) Hydrogen gas is colorless (3) Hydrogen gas has a density of 0.000 9 g/cm3 at STP (4) Hydrogen gas has a boiling point of 20. K at standard pressure. 5. Which unit can be used to express solution concentration? (1) J/mol (3) mol/L (2) L/mol (4) mol/s 6. Given the equation representing a system at equilibrium: H2O(s) < ===== > H2O(l) At which temperature does this equilibrium exist at 101.3 kilopascals? (1) 0 K (3) 32 K (2) 0oC (4) 273oC 7. Which metal is more active than Ni and less active then Zn? (1) Cu (3) Mg (2) Cr (4) Pb
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93
Day 19:
continue.
14. The graph below represents the relationship between temperature and time as heat is added to a sample of H2O.
Which statement correctly describes the energy of the particles of the sample during interval BC ? (1) Potential energy decreases and average kinetic energy increases (2) Potential energy increases and average kinetic energy decreases (3) Potential energy increases and average kinetic energy remains the same. (4) Potential energy remains the same and average kinetic energy increases. 15. Given the balanced equation representing a reaction: C3H8(g ) + 5O2(g) ---- > 3CO2(g) + 4H2O(l) What is the total number of moles of O2(g) required for the complete combustion of 1.5 moles of C3H8(g) ? (1) 0.30 mol (2) 1.5 mol
(3) 4.5 mol (4) 7.5 mol
Day 19 Stop. Correct your answers and note how many correct Points
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95
Day 19: 9)
Answers and Explanations
4 Recall: Hydroxide (OH-) are produced by bases. Note: Bases(such as KOH) are listed on Table L
10) 2
Note: Of all the changes to the reaction given as choices , a decrease in temp is the change that will produce slower rate (proceed slower) All other changes will produce faster rates of reaction
11) 1
Note: Table G shows solubility of substances Note: At any given temperature, the substance closest to bottom is the least soluble at that temperature. Note: At 6.0oC, KClO3 curve is closest to the bottom
12) 2
Recall: an excited state configuration is not the same as what’s on the Periodic Table for a given element. Note: The correct choice has 10 e- = # of e- in a neon atom. But the configuration is differently arranged from one given on Periodic Table for a ground state Ne.
13) 1 Recall: decay mode are given on Table N Note: according to Table N, both Ca-37 and Fe-53 decay by emitting a positron (β+) 14) 3
Note: During BC, temperature is constant (therefore, no change in average kinetic energy) Recall: When kinetic energy is constant, potential energy changes.
15) 4
Note: This is a mole proportion problem Setup mole proportion to solve: 1 C3H8(g ) + 5O2(g) ---- > 3CO2(g) + 4H2O(l)
1.5 1 1.5
=
x 5 x
x = (1.5) (5) = 7.5 mol
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97
Day 20: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
Base your answers to questions 1 and 2 on the information below.
In 1987, J.J. Thompson demonstrated in an experiment that cathode rays were deflected by an electric field. This suggested that cathode rays were composed of negatively charged particles found in all atoms. Thomson concluded that the atom was a positively charged sphere of almost uniform density in which negatively charged particles were embedded. The total negative charge in an atom was balanced by the positive charge, making the atom electrically neutral. In the early 1900’s, Ernest Rutherford bombarded a very thin sheet of gold foil with alpha particles. After interpreting the results of the gold foil experiment, Rutherford proposed a more sophisticated model of the atom. 1. State one conclusion from Rutherford’s experiment that contradicts one conclusion made by Thomson. [1]
2. State one aspect of the modern model of the atom that agrees with a conclusion made by Thomson. [1]
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99
Day 20:
continue.
Base your answer to questions 6 through 8 on the information below.
During a bread-making process, glucose is converted to ethanol and carbon dioxide, causing the bread dough to rise. Zymase, an enzyme produced by yeast, is a catalyst needed for this reaction. 6. Balance the equation below for the reaction that causes bread dough to rise, using the smallest whole-number coefficients. [1] ___ C6H12O6
zymase ------- > ___C2H5OH + ___CO2
7. In the space in your answer booklet, draw a structural formulas for the alcohol formed in this reaction. [1]
8. State the effect of zymase on the activation energy for this reaction. [1]
------------------------------------------------------------------------9. Explain, in terms of collision theory, why the rate of a chemical reaction increases with an increase in temperature. [1]
10. Base on the Periodic Table, explain why chlorine and bromine have similar chemical properties [1]
Day 20 Stop. Correct your answers and note how many correct Points Copyright © 2011 E3 Scholastic Publishing. All Rights Reserved
101
Day 20:
6)
C6H12O6
Answers and Explanations: continue
------- > 2C2H5OH +
2CO2
Recall: a balanced equation must show conservation of atoms; Number of each atom on both sides must be the same Note: The coefficients above allows there to be 6 C, 12 H, and 6 O atoms on each side of the equation . 7)
H H I I H – C – C – OH I I H H
Note: The position of the OH may vary
8) Zymase (a catalyst) lowers activation energy for the reaction. or Zymase provides alternate pathways for the reaction. 9) When temperature increases, reaction rate increases because there will be an increase in the kinetic energy of the particles and the frequency of collisions. 10) Cl and Br have similar chemical properties because: (answers may vary) Cl and Br are in the same Group (17). Cl and Br are halogens Cl and Br have the same number of valance electrons Cl and Br have similar oxidation state.
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103
Day 21: Start:
20 Multiple Choice questions
Answer all 20 questions on this day before stopping.
1. Which subatomic particles are located in the nucleus of a neon atom? (1) electrons and positrons (2) electrons and neutrons (3) protons and neutrons (4) protons and electrons 2. An atom of argon rarely bonds to an atom of another element because an argon atom has (1) 8 valance electrons (2) 2 electrons in the first shell (3) 3 electron shells (4) 22 neutrons 3. Bronze contains 90 to 95 percent copper and 5 to 10 percent tin. Because these percentages can vary, bronze is classified as (1) a compound (3) a mixture (2) an element (4) a substance 4. Which compound has hydrogen bonding between its molecules? (1) CH4 (3) KH (2) CaH2 (4) NH3 5. At STP, which list of elements contains a solid, a liquid, and a gas? (1) Hf, Hg, He (3) Ba, Br2, B (2) Cr, Cl2, C (4) Se, Sn, Sr 6. The three isomers of pentane have different (1) formula mass (3) molecular mass (2) empirical formula (4) structural formula 7. Which molecule contains a nonpolar covalent bond? (1) O = C = O (3) Br – Br Cl I
(2) C = O
(4) Cl – C – Cl I
Cl
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Day 21:
continue.
15. Which structural formula is correct for 2-methyl-3-pentanol?
16. The atomic mass of element A is 63.6 atomic mass units. The only naturally occurring isotopes of element A are A-63 and A-65. The percent abundances in a naturally occurring sample of element A are closest to (1) 31% A-63 and 69% A-65 (2) 50% A-63 and 50% A-65 (3) 69% A-63 and 31% A-65 (4) 100% A-63 and 0% A-65 17. Given the balance equation: 4Fe(s) + 3O2(g)
---- > 2Fe2O3(s) + 1640KJ
Which phrase best describes this reaction? (1) endothermic with ∆H = +1640 KJ (2) endothermic with ∆H = -1640 KJ (3) exothermic with ∆H = +1640 KJ (4) exothermic with ∆H = -1640 KJ
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109
Day 21:
Answers and Explanations
9) 3 Recall: Fusion is a nuclear process of joining two smaller nuclei of H to form a larger nucleus of He. 10) 2
Note: If the sample contains 74.5 % by mass of chlorine, the remaining percent of 25.5 % will be of the mass of Mg Relate: the mass of Mg in sample is, therefore, 25.5 % of 190.2 g. Calculate 25.5 % of 190.2 g to get mass of Magnesium (Mg). 0.255 x 190.2 = 48.5 g
11) 2 Recall: sublimation is a phase change of solid ----- > gas 12) 1 Note: correct choice is a fact related to all Arrhenius acids 13) 4 Recall the four common types of nuclear reactions are : Nuclear energy reactions: fission and fusion Natural Transmutation: alpha and beta decay, position emission. Artificial Transmutation 14) 1 Recall: A positive ion is formed when an atom loses its valance electrons. Note: The + ion is always smaller because the atom also loses the entire valance shell. 15) 2 Note: This structure is correct because it shows: a methyl (CH3) group on the 2nd C atom (2-methyl) an OH group on the 3rd C (3-pentanol) The long chain has 5 C atoms (pent-)
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111
Day 22: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
Base your answers to question 1 through 3 on the information below.
The compound NH4Br(s) and NH3(g) are soluble in water. Solubility data for NH4Br(s) in water are listed in the table below. Solubility of NH4Br in H2O Temperature (oC)
Mass of NH4Br per 100. g of H2O (g)
0
60.
20.
75.
40.
90.
60.
105
80.
120
100.
135
1. On the grid to the right, plot the data from the data table. Circle and connect the points. [1] 2. Determine the total mass of NH4Br(s) that must be dissolved in 200. grams of H2O at 60.oC to produce a saturated solution. [1]
3. Compare the solubility of NH4Br(s) and NH3(g), each in 100. grams of H2O, as temperature increases at standard pressure. Your response must include both NH4Br(s) and NH3(g). [1]
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113
Day 22:
continue.
8. What is the chemical formula for tin (II) fluoride? [1]
9. How many parts per million of fluoride ions are present in the analyzed sample? [1]
10. Is the town’s drinking water safe to drink? support your decision using information in the passage and your calculated fluoride level in question 9. [1]
Day 22 Stop. Correct your answers and note how many correct Points
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115
Day 22:
7)
.. :F: ..
8) SnF2
Answers and Explanations
Note: Fluoride ion is F- (See Periodic Table for charge on a fluorine) Recall: A Lewis electron-dot diagram for all negative (-) ions (except H-) must show 8 dots around the ion symbol. Use criss-cross method to determine correct formula. tin (II) fluoride Sn2+ F1-
Recall: (II) means +2 charge for Sn
SnF2 9) 14.3 ppm Use part per million equation on Table T to calculate. ppm = ppm =
Grams of solute Grams of solution 0.00250 (175 g + .00250)
x 100000 x 1000000 = 14.3 ppm
10) No Note: because the ppm concentration of F- ion (14.3 ppm) exceeds the safe limit of F- ion (4 ppm) set by Environmental Protection Agency.
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117
Day 23: Start:
20 Multiple Choice questions
Answer all 20 questions on this day before stopping.
1. Compared to a proton, an electron has (1) greater quantity of charge and the same sign (2) greater quantity of charge and the opposite sign (3) the same quantity of charge and the same sign (4) the same quantity of charge and the opposite sign 2. Which two notation represents atoms that are isotopes of the same element? 121
119
50
50
(1) Sn and (2)
121 50
Sn and
Sn
121 50
Sn
(3) (4)
19 8
O and
39 17
Cl and
19 9 39 19
F K
3. Which substance can be decomposed by a chemical change? (1) calcium (3) copper (2) potassium (4) ammonia 4. Based on Reference Table S, the atoms of which of these elements have the strongest attraction for electrons in a chemical bond? (1) N (3) P (2) Na (4) Pt 5. Which Period 4 element has the most metallic properties? (1) As (3) Ge (2) Br (4) Se 6. What is the total number of pairs of electrons shared in a molecule of N2? (1) one pair (3) three pairs (2) two pairs (4) four pair 7. Which statement best describes the shape and volume of an aluminum cylinder at STP? (1) It has definite shape and a definite volume (2) It has definite shape and no definite volume (3) It has no definite shape and a definite volume (4) It has no definite shape and no definite volume
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119
Day 23:
continue.
13. Which chemical equation is correctly balanced? (1) H2(g) + O2(g) ----- > H2O(g) (2) N2(g) + H2(g) ------ > NH3(g) (3) 2NaCl(s) --------- > Na(s) + Cl2(g) (4) 2KCl(s) ----- > 2K(s) + Cl2(g) 14. Which type of bond is found in sodium bromide? (1) covalent (3) ionic (2) hydrogen (4) metallic 15. Which Lewis electron dot is correct for CO2?
16. Two sample of gold that have different temperatures are placed in contact with one another. Heat will flow spontaneously from a sample of gold at 60oC to a sample of gold that has a temperature of (1) 50oC (3) 70oC (2) 60oC (4) 80oC
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123
Day 23: 9) 3
Answers and Explanations: continue
Note: The correct choice is a definition of an electrolyte.
10) 2 Note: The correct choice is a fact related to systems in nature 11) 2 Note: You are comparing a higher NaCl solution concentration (0.8 M) to a lower concentration (0.1 M). Recall: The higher the concentration, the higher the boiling point and the lower the freezing point of a solution. 12) 2
Note: The electron transition in the question is from a higher shell (3rd) to a lower shell (2nd) Recall: Energy is released (emitted) by an electron as the electron moves from a higher to lower shell.
13) 4 Recall: Equation is balanced when the number of each atom is equal on both sides (demonstrates conservation) Note: The correct equation has 2 K and 2 Cl on both sides 14) 3
Note: sodium bromide is composed of a metal (Na) and a nonmetal (Br) Recall: Ionic bond is formed between a metal and a nonmetal.
15) 3 Recall: Structure of CO2 is O = C = O This Lewis structure for choice 3 is correct because: . It shows the correct number of shared electrons . It shows all atoms with octet (8) of electrons 16) 1 Recall: Heat only flows from high temp object to lower temp. Note: This choice is correct b/c heat will from a gold at 60oC to a gold with a lower temp (50oC) 17) 4 Recall these equilibrium facts: Concentration (measureable quantity) of substances must be constant. Rate of forward and reveres reactions must be equal
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125
Day 24: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
Base your answers to questions 1 through 2 on the balanced equation below.
Fe(s)
+ HNO3(aq) ---- > Fe(NO3)2(aq) + H2(g)
1. What is the total number of oxygen atoms represented in the formula of the iron compound produced? [1]
2. Explain, using information from Reference Table J, why this reaction is spontaneous.
Base your answers to questions 3 and 4 on the information below.
In a titration, 15.65 millimeters of a KOH(aq) solution exactly neutralized 10.00 millimeters of a 1.22 M HCl(aq) solution. 3. Complete the equation below for the titration reaction by writing the formula for each product. [1] KOH + HCl
---- >
_____ + ______
4. In the space below, show a correct numerical setup for calculating the molarity of KOH(aq) solution. [1]
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127
Day 24:
continue.
Base your answers to questions 7 and 8 on the information below.
An atom has an atomic number of 9, a mass number of 19, and an electron configuration of 2 – 6 – 1. 7. What is the total number of neutrons in this atom? [1] 8. Explain why the number of electrons in the second and third shells shows that this atom is in an excited state? [1]
Base your answers to question 9 and 10 on the information below.
The balanced equation below represents the reaction between magnesium metal and hydrochloric acid to produce aqueous magnesium chloride and hydrogen gas. Mg(s) + 2HCl(aq) ---- > MgCl2(aq)
+ H2(g)
A piece of Mg(s) has a volume of 0.0640 cubic centimeters. This piece of Mg(s) reacts completely with HCl(aq) to produce H2(g). The H2(g) produced has a volume of 112 millimeters and a pressure of 1.00 atmosphere at 298 K. 9. The volume of the piece of Mg(s) is expressed to what number of significant figures? [1] 10. In the space below, show a correct numerical setup for calculating the volume of the H2(g) produced if the conditions are changed to STP. [1]
Day 24 Stop. Correct your answers and note how many correct Points Copyright © 2011 E3 Scholastic Publishing. All Rights Reserved
129
Day 24: 7) 10
Recall:
Answers and Explanations: continue Neutrons = Mass # - Atomic # (protons) 19
-
9 = 10
8) The configuration is in the excited state because the 3rd shell only has 6 (not full with 8) while the 2nd contains an electron. 9) 3
Note: In the number 0.0640 : the last 3 digits are significant Recall the following rules for counting significant numbers: .All zero to start a number (0.0 640) are NOT significant .All Real numbers (0.064 0) are significant .If a number has a decimal point, all zeros at the end of the number are significant 0.0640)
10) Note: This is a gas law problem Determine factors from passage and question P1 = 1 atm P1 = 1 atm STP T1 = 298 K T2 = 273 V1 = 112 ml V2 = unknown Use the Combined Gas law equation on Table T to setup P1V1 P2V2 = T1 T2 (1) (112) 298
=
or V2 =
(1) (V2) 273 your setup may vary from these two setups
1(273)(112) 298
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Day 25: Start:
20 Multiple Choice questions
Answer all 20 questions on this day before stopping.
1. Which subatomic particles has a negative charge? (1) proton (3) neutron (2) electron (4) positron 2. Which statement best describes the nucleus of an aluminum atom? (1) It has a charge of +13 and is surrounded by 10 electrons. (2) It has a charge of +13 and is surrounded by 13 electrons. (3) It has a charge of -13 and is surrounded by 10 electrons. (4) It has a charge of -13 and is surrounded by 13 electrons. 3. Two different samples decomposed when heated. Only one of the samples is soluble in water. Based on this information, these two samples are (1) both the same element (2) two different elements (3) both the same compound (4) two different compounds 4. Which of these elements has the lowest melting point? (1) Li (3) K (2) Na (4) Rb 5. Which list consists of types of chemical formulas? (1) atoms, ions, molecules (2) metals, nonmetals, metalloids (3) empirical, molecular, structural (4) synthesis, decomposition, neutralization 6. Which formula represents a nonpolar molecule? (1) H2S (3) CH4 (2) HCl (4) NH4 7. An aqueous solution of sodium chloride is best described as a (1) homogeneous compound (2) homogeneous mixture (3) heterogeneous compound (4) heterogeneous mixture
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Day 25:
continue.
12. What is the oxidation number assigned to manganese in KMnO4? (1) +7 (3) +3 (2) +2 (4) +4 13. A student tested a 0.1 M aqueous solution and made the following observations: . conducts electricity . turns blue litmus to red . reacts with Zn(s) to produce gas bubbles. Which compound could be the solute in this solution? (1) CH3OH (2) LiBr
(3) HBr (4) LiOH
14. Which equation represents a neutralization reaction? (1) 4Fe(s) + 3O2(g) ------ > 2Fe2O3(s) (2) 2H2(g) + O2(g) ------ > 2H2O(l) (3) HNO3(aq) + KOH(aq) --- > KNO3(aq) + H2O(l) (4) AgNO3(aq) + KCl(aq) ------- > KNO3(aq) + AgCl(s) 15. Given the balance equation representing a redox reaction: 2Al + 3Cu2+ ---- > 2Al3+ + 3Cu Which statement is true about this reaction? (1) Each Al loses 2e- and each Cu2+ gains 3e(2) Each Al loses 3e- and each Cu2+ gains 2e(3) Each Al3+ gains 2e- and each Cu loses 3e(4) Each Al3+ gains 3e- and each Cu loses 2e16. The percent composition by mass of magnesium in MgBr2 (gram-formula mass = 184 grams/mole) is equal to (1) 24 x 100 184 (2) 160. x 100 184
(3) 184 x 100 24 (4) 184 x 100 160.
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Day 25:
continue.
19. Which diagram represents the nucleus of an atom of 14 n 27 p
27Al?
13
27 n 13 p (1)
14 n 13 p (2)
(3) 40 n 13 p (4)
(2)
(4)
20. The chart below shows the spontaneous nuclear decay of U-238 to Th-234 to Pa-234 to U-234.
What is the correct order of nuclear decay modes for the change from U-238 to U-234? (1) β-decay, γ decay, β-decay (2) β-decay, β-decay, α decay (3) α decay, α decay, β-decay (4) α decay, β-decay, β-decay
Day 25 Stop. Correct your answers and note how many correct Points
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Day 25:
Answers and Explanations: continue
11) 2 Note: this configuration is correct b/c the numbers in the configuration add up to 17 (# of electrons in Cl atom) BUT, arranged differently from the ground State configuration on the Periodic Table. 12) 1 Recall: sum of charges in a compound must equal zero. Note: This charge of Mn (+7) adds to charge of K (+1) and the total charge of O (-8) to equal zero. 13) 3
Note: the observations describe properties of acids. Note: HBr is an acid (Use Table K)
14) 3 Recall: Neutralization is a reaction of an acid (HNO3) with a base (KOH) to produce salt (KNO3) and water (H2O) as products. 15) 2
Note the following oxidation number changes of Al and Cu2+. Al --------- > Al3+ + 3e- (each Al loses 3 e-) Cu2+ + 2e- ----- > Cu (each Cu2+ gains 2 e-)
16)
1
Use Table T percent composition equation to setup: % Mg = % Mg =
Total Mass of Mg Gram-formula mass 24
x 100 x 100
184 17) 4 Recall: The difference between the Potential Energy (PE) of the products and the Potential Energy of the reactants is ∆H (heat of reaction) ∆H = PE of products – PE of reactants
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Day 26: Start:
10 Constructed Response Questions
Answer all 10 questions on this day before stopping.
Base your answers to 1 through 3 on the information below.
In a laboratory, 0.100 mole of colorless hydrogen iodide gas at room temperature is placed in a 1.00-liter flask. The flask is sealed and warmed, causing the HI(g) to start decomposing to H2(g) and I2(g). Then the temperature of the contents of the flask is kept constant. During this reaction, the contents of the flask change to a pale purple-colored mixture of HI(g), H2(g), and I2(g). When the color of the mixture in the flask stops changing, the concentration of I2(g) is determine to be 0.013 mole per liter. The relationship between concentration and time for the reactant and products is shown in the graph below.
1. Write a balanced equation to represent the decomposition reaction occurring in the flask. [1]
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Day 26:
continue.
Base your answers to questions 22 to 24 on the information below.
The hydrocarbon 2-methylpropane reacts with iodine as represented by the balanced equation below. At Standard pressure, the boiling point of 2-methylpropane is lower than the boiling point of 2-iodo-2-methylpropane.
6. To which class of organic compound does this organic product belong? [1] 7. Explain, in terms of bonding, why the hydrocarbon 2-methylpropane is saturated. [1]
8. Explain the difference in the boiling points of 2-methylpropane and 2-iodo-2-methylpropane in terms of both molecular polarity and intermolecular forces. [2] Molecular polarity: [1]
Intermolecular forces: [1]
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Day 26:
Answers and Explanations: continue
5) Hit the solid with a hammer to see if it flattens into a thin sheet. Recall: Malleability describes how easily a solid can be flattened when struck. 6) Halide or organic halide Note: The product contains iodine (a halogen, Group 17)
7) The hydrocarbon 2-methylpropane is saturated because it contains all single bonds between the carbon atoms.
8)
Molecular polarity: 2-methylpropane has a lower boiling point than 2-iodo-2-methylpropane because it is less polar.
Intermolecular forces: 2-methylpropane has a lower boiling point than 2-iodo-2-methylpropane because it has weaker intermolecular forces.
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Day 27: Chemistry Regents Exam: August 2009 Start: Answer all questions in Part A and B-1 before stopping Part A:
Answer all questions in this part Directions (1 – 30): For each statement or question, write on the separate answer sheet the number of the word or expression that, of those given, best completes the statement or answer the question. Some questions may require the use of the Reference tables for Physical setting/Chemistry. 1. Which particle has the least mass? (1) 4He (2) 1H
(3) 1n (4) oe
2. What information is necessary to determine the atomic mass of the element chlorine? (1) The atomic mass of each artificially produced isotope of chlorine, only (2) The relative abundances of each naturally occurring isotope of chlorine, only (3) The atomic mass and the relative abundances of each naturally occurring isotope of chlorine (4) The atomic mass and the relative abundances of each naturally occurring and artificially produced isotope of chlorine 3. In an atom of argon-40, the number of protons (1) equals the number of electrons (2) equals the number of neutrons (3) is less than the number of electrons (4) is greater than the number of electrons 4. An electron is a sodium atom moves from the third shell to the fourth shell. This change is a result of the atom (1) absorbing energy (3) gaining an electron (2) releasing energy (4) losing an electron
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Day 27: Chemistry Regents Exam: August 2009 Part A.
Continue
10. Why is a molecule of CO2 nonpolar even though the bonds between the carbon atom and the oxygen atoms are polar? (1) The shape of the CO2 molecule is symmetrical. (2) The shape of the CO2 molecule is asymmetrical. (3) The CO2 molecule has a deficiency of electrons. (4) The CO2 molecule has an excess of electrons. 11. Which formula represents a molecular compound? (1) HI (3) KCl (2) KI (4) LiCl 12. Which element has the greatest density at STP? (1) Scandium (3) Silicon (2) Selenium (4) Sodium 13. Particles are arranged in a crystal structure in a sample of (1) H2(g) (3) Ar(g) (2) Br2(l) (4) Ag(s) 14. The relatively high boiling point of water is due to water having (1) hydrogen bonding (2) metallic bonding (3) nonpolar covalent bonding (4) strong ionic bonding 15. Matter is classified as (1) substances, only (2) substances or as a mixture of substances (3) homogeneous mixture, only (4) homogeneous mixture or as a heterogeneous mixture 16. Which substance can not be decomposed by chemical changes? (1) ammonia (3) propanol (2) copper (4) water Copyright © 2011 E3 Scholastic Publishing. All Rights Reserved
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Day 27: Chemistry Regents Exam: August 2009 Part A.
Continue
21. According to the kinetic molecular theory, which statement describes the particles in a sample of an ideal gas? (1) the force of attraction between the gas particles is strong (2) The motion of the gas particles is random and straight-line (3) The collisions between the gas particles cannot result in a transfer of energy between the particles (4) The separation between the gas particles is smaller than the size of the gas particles themselves. 22. The activation energy of a chemical reaction can be decreased by the addition of (1) a catalyst (3) electrical energy (2) an indicator (4) thermal energy 23. A straight-chain hydrocarbon that has only one double bond in each molecule has the general formula (1) CnH2n-6 (3) CnH2n (2) CnH2n-2 (4) CnH2n+2 24. Why can an increase in temperature lead to more effective collision between reactant particles and an increase in the rate of a chemical reaction? (1) The activation energy of the reaction increases. (2) The activation energy of the reaction decreases. (3) The number of molecules with sufficient energy to react increases. (4) The number of molecules with sufficient energy to react decreases. 25. Which reaction results in the production of soap? (1) esterification (3) polymerization (2) fermentation (4) saponification
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Day 27: Chemistry Regents Exam: August 2009 Part B-1: Answer all questions in this part. Directions (31 – 50): For each statement or question, write on the separate answer sheet the number of the word or expression that, of those given, best completes the statement or answer the question. Some questions may require the use of the Reference tables for Physical setting/Chemistry. 31. Which electron configuration represents an excited state for a potassium atom? (1) 2-8-7-1 (3) 2-8-8-1 (2) 2-8-7-2 (4) 2-8-8-2 32. A sample of an element is malleable and can conduct electricity. This element could be (1) H (3) S (2) He (4) Sn 33. Which general trend is demonstrated by Group 17 elements as they are considered in order from top to bottom on the Periodic Table? (1) a decrease in atomic radius (2) a decrease in electronegativity (3) an increase in first ionization energy (4) an increase in nonmetallic behavior 34. Which element is a liquid at 758 K and standard pressure? (1) gold (3) platinum (2) silver (4) thallium 35. Which equation represents a decomposition reaction? (1) CaCO3(s) ------- > CaO(s) + CO2(g) (2) Cu(s) + 2AgNO3(aq) ---- > 2Ag (s) + Cu(NO3)2(aq) (3) 2H2(g) + O2(g) --- > 2H2O(l) (4) KOH(aq) + HCl(aq) --- > KCl(aq) + H2O(l)
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Day 27: Chemistry Regents Exam: August 2009 Part B-1. Continue. 41. Given the bright-line spectra of the three elements and the spectrum of a mixture formed from at least two off these elements.
Which elements are present in this mixture? (1) E and D, only (2) E and G, only
(3) D and G, only (4) D, E, and G
42. Given the balanced particle-diagram equation:
Which statement describes the type of change and the chemical properties of the product and reactant? (1) The equation represents a physical change, with the product and the reactants having different chemical properties. (2) The equation represents a physical change, with the product and the reactants having identical chemical properties (3) The equation represents a chemical change, with the product and the reactants having different chemical properties. (4) The equation represents a chemical change, with the product and the reactants having identical chemical properties.
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Day 27: Chemistry Regents Exam: August 2009 Part B-1. Continue. 47. Which formula represents an unsaturated hydrocarbon?
48. What is the oxidation state of nitrogen in the compound NH4Br? (1) -1 (3) -3 (2) +2 (4) +4 49. A student completes a titration by adding 12.0 millimeters of NaOH(aq) of unknown concentration to 16.0 millimeters of 0.15 M HCl(aq). What is the molar concentration of the NaOH(aq)? (1) 0.11 M (3) 1.1 M (2) 0.20 M (4) 5.0 M 50. What is the half-life of a radioisotope if 25.0 grams of an original 200. gram sample of the isotope remains unchanged after 11.46 days? (1) 2.87 d (3) 11.46 d (2) 3.82 d (4) 34.38
Day 27 Stop: Correct your answers and note how many correct Points
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Day 28: Physical Setting: Chemistry Regents Exam August 2009
Start: Answer all questions in Part B-2 and Part C before stopping Part B-2: Answer all questions in this part Directions (51-63): Record your answers in the spaces provided in your answer booklet. Some questions may require the use of the Reference Tables for Physical Setting/Chemistry. 51. Identify the element in Period 3 of the Periodic Table that reacts with oxygen to form an ionic compound represented by the formula X2O. [1] 52. Given the unbalanced equation representing a reaction: 2C6H12 + 7O2 ---- > 4CO2 + 6H2O Determine the total number of moles of oxygen that react completely with 8.0 moles of C2H6. [1] _____ mol 53. On the potential energy diagram in your answer booklet, draw an arrow to represent the activation energy of the forward reaction. [1]
54. Describe the electrons in an atom of carbon in the ground state. Your response must include: . the charge of an electron [1] . the location of electrons based on the wave-mechanical model [1] . the total number of electrons in a carbon atom [1]
55. Determine the mass of 5.20 moles of C6H12 (gram-formula mass = 84.2 grams/mole). [1] _____ g Copyright © 2011 E3 Scholastic Publishing. All Rights Reserved
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Day 28: Chemistry Regents Exam: August 2009 Part B-1. Continue. Base your answers to questions 59 though 63 on the information below:
Bond energy is the amount of energy required to break a chemical bond. The table below gives a formula and the carbon-nitrogen bond energy for selected nitrogen compounds. Compound
Formula
hydrogen cyanide
H–C=N
890.
isocyanic acid
H–N=C=O
615
methaneamine
Carbon-Nitrogen Bond Energy (KJ/mol)
H I
H–C–N–H I
I
293
H H 59. Describe, in terms of electrons, the type of bonding between the carbon atom and the nitrogen atom in a molecule of methanamide. [1] 60. Identify the noble gas that has atoms in the ground state with the same electron configuration as the nitrogen in a molecule of isocyanic acid. [1] 61. State the relationship between the number of electrons in a carbonnitrogen bond and carbon-nitrogen bond energy. [1]
62. Explain, in terms of charge distribution, why a molecule of hydrogen cyanide is polar. [1] 63. A 3.2-gram sample of air contains 0.000 74 gram of hydrogen cyanide. Determine the concentration, in parts per million, of the hydrogen cyanide in this sample. [1] ____ ppm
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Day 28: Chemistry Regents Exam: August 2009 Part C. Continue. Base your answer to questions 65 through 67 on the information below.
A student used blue litmus paper and phenolphthalein paper as an indicator to test the pH of distilled water and five aqueous household solutions. Then the student used a pH meter to measure the pH of the distilled water and each solution. The results of the student’s work are recorded in the table below. Liquid Tested Color of Blue Litmus Paper
Color of Measured Phenolphthalein pH value Paper Using a pH meter
2% milk
blue
colorless
6.4
distilled water
blue
colorless
7.0
household ammonia
blue
pink
11.5
lemon juice
red
colorless
2.3
tomato juice
red
colorless
4.4
vinegar
red
colorless
3.3
65. Identify the liquid tested that has the lowest hydronium ion concentration. [1]
66. Explain, in terms of the pH range for the color change on Reference Table M, why the litmus is not appropriate to differentiate the acidity levels of tomato juice and vinegar. [1]
67. Based on the measured pH values, identify the liquid tested that is 10 times more acidic than vinegar. [1]
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Day 28: Chemistry Regents Exam: August 2009 Part C. Continue. Base your answers to questions 73 through 76 on the information below.
In a laboratory investigation, a student constructs a voltaic cell with iron and copper electrodes. Another student constructs a voltaic cell with zinc and iron electrodes. Testing the cells during operation enables the students to write the balanced ionic equations below: Cell with iron and copper electrodes: Cu2+(aq) + Fe(s) ---- > Cu(s) + Fe2+(aq) Cell with zinc and iron electrodes: Fe2+(aq) + Zn(s) ----- > Fe(s) + Zn2+(aq 73. State evidence from the balance equation for the cell with iron and copper electrodes that indicates the reaction in the cell is an oxidation-reduction reaction. [1]
74. Identify the particles transferred between Fe2+ and Zn during the reaction in the cell with zinc and iron electrodes. [1]
75. Write a balance half-reaction equation for the reduction that takes place in the cell with zinc and iron electrodes. [1]
76. State the relative activity for the three metals used in these two voltaic cells. [1]
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Day 28: Chemistry Regents Exam: August 2009 Part C. Continue. Base your answers to questions 80 through 81 on the information below.
Scientists are investigating the production of energy using hydrogen-2 nuclei (deuterons) and hydrogen-3 nuclei (tritons). The balanced equation below represents one nuclear reaction between two deuterons. 2H 1
+
2H 1
--- > 23 He +
1n 0
+ 5.23 x10-13 J
80. State, in terms of subatomic particles, how a deuteron differs from a triton. [1]
81. Identify the type of nuclear reaction represented by the equation. [1]
Day 28 Stop: Correct your answers and note how many correct Points
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Answer Booklet: August 2009
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169
Answer Booklet: August 2009
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171
Answer Booklet: August 2009
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Day 28: Chemistry Regents Exam August 2009 Answers Part B-2
continue
59) .Covalent bond .Electrons are shared in the bond 60) Ne, Neon, element number 10 61) As the number of shared electrons in a C – N bond increases, the bond energy increases OR Less energy is required to break a single C – N than to break a triple C – N bond. 62) The molecule has an asymmetrical structure The molecule has unequal distribution of charges 63) 230 ppm or 2.31 x 102 ppm
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Day 28: Chemistry Regents Exam: August 2009 Answers Part C continue. 75) Fe2+ + 2e- ---- > Fe 76) Zinc is more reactive than iron, and iron is more reactive than copper. The order of decreasing activity is Zn, Fe, Cu Copper is least active and zinc is most active 77) d =
m
V 8.75 g/cm3
=
129.5 g 14.8 cm3
or
129.5 14.8
78) 1084oC 79) 13.8 g 80) A deuteron has one neutron a triton has two neutrons 81) Fusion or
thermonuclear fusion or nuclear fusion
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177
Day 29: Chemistry Regents Exam: January 2010 Start: Answer all questions in Part A and B-1 before stopping Part A: Answer all questions in this part Directions (1 – 30): For each statement or question, write on the separate answer sheet the number of the word or expression that, of those given, best completes the statement or answer the question. Some questions may require the use of the Reference tables for Physical setting/Chemistry. 1. Which two particles have opposite charges? (1) an electron and a neutron (2) an electron and a proton (3) a proton and a neutron (4) a proton and a positron 2. Which statement describes how an atom in the ground state becomes excited? (1) The atom absorbs energy, and one or more electrons move to a higher electron shell (2) The atom absorbs energy, and one or more electrons move to a lower electron shell (3) The atom releases energy, and one or more electrons move to a higher electron shell (4) The atom releases energy, and one or more electron move to a lower electron shell 3. An element that has a low first ionization energy and good conductivity of heat and electricity is classified as a (1) metal (3) nonmetal (2) metalloid (4) noble gas 4. The chemical properties of calcium are most similar to the chemical properties of (1) Ar (3) Mg (2) K (4) Sc 5. Which element is a liquid at STP? (1) argon (2) bromine
(3) chlorine (4) sulfur
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Day 29: Chemistry Regents Exam: January 2010 Part A. Continue. 13. Which element has an atom with the greatest tendency to attract electrons in a chemical bond? (1) carbon (3) silicon (2) chlorine (4) sulfur 14. The nitrogen atom in a molecule of N2 share a total of (1) one pair of electrons (2) one pair of protons (3) three pairs of electrons (4) three pairs of protons 15. An ionic compound is formed when there is a reaction between the elements of (1) strontium and chlorine (2) hydrogen and chlorine (3) nitrogen and oxygen (4) sulfur and oxygen 16. Which compound has both ionic and covalent bonding? (1) CaCO3 (3) CH3OH (2) CH2Cl2 (4) C6H12O6 17. The liquids hexane and water are placed in a test tube. The test tube is stoppered, shaken, and placed in a test tube rack. The liquid separated into two distinct layers because hexane and water have different (1) formula mass (2) molecular polarities (3) pH value (4) specific heat 18. Which statement describes the particles of an ideal gas based on the kinetic molecular theory? (1) The gas particles are relatively far apart and have negligible volume. (2) The gas particles are in constant, nonlinear motion (3) The gas particles have attractive forces between them. (4) The gas particles have collisions without transferring energy.
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181
Day 29: Chemistry Regents Exam: January 2010 Part A. Continue. 25. When one compound dissolves in water , the only positive ion produced in the solution is H3O+(aq). This compound is classified as (1) a salt (2) a hydrocarbon (3) an Arrhenius acid (4) an Arrhenius base 26. Which nuclear emission has the greatest mass and the least penetrating power? (1) an alpha particle (3) a neutron (2) a beta particle (4) a positron 27. Which radioisotope has an atom that emits a particle with a mass number of 0 amu and a charge of +1? (1) 3H (3) 19Ne (2) 16Ne (4) 239Pu 28. In which type of reaction do two lighter nuclei combine to form one heavier nucleus? (1) combustion (3) nuclear fission (2) reduction (4) nuclear fusion 29. For which compound is the process of dissolving in water exothermic? (1) NaCl (3) NH4Cl (2) NaOH (4) NH4NO 30. Which quantity must be equal for a chemical reaction at equilibrium? (1) the activation energies of the forward and reverse reaction (2) the rates of the forward and reverse reactions (3) the concentrations of the reactants and products (4) the potential energies of the reactants and products
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Day 29: Chemistry Regents Exam: January 2010 Part B-1. Continue. 36. Given the balanced equation representing a reaction: CaO(s) + CO2 --- > CaCO3(s) + heat What is the total mass of CaO(s) that reacts completely with 88 grams of CO2(g) to produce 200. grams of CaCO3(s)? (1) 56 g (2) 88 g
(3) 112 (g) (4) 288 g
37. What is the empirical formula of a compound that has a carbon-tohydrogen ratio of 2 to 6? (1) CH3 (3) C3H (2) C2H6 (4) C6H2 38. Given the balanced equation representing a reaction: H2(g) + Cl2(g) --- > 2HCl(g) + energy Which statement describes the energy changes in this reaction? (1) Energy is absorbed as bonds are formed, only. (2) Energy is released as bond are broken, only (3) Energy is absorbed as bonds are broken, and energy is released as bonds are formed. (4) Energy is absorbed as bonds are formed, and energy is released as bonds are broken. 39. Which solution has the highest boiling point at standard pressure? (1) 0.10 M KCl(aq) (2) 0.10 M K2SO4(aq) (3) 0.10 M K3PO4(aq) (4) 0.10 M KNO3(aq) 40. What is the molarity of 1.5 liters of an aqueous solution that contains 52 grams of lithium fluoride, LiF (gram-formula mass = 26 grams/mole)? (1) 1.3 M (3) 3.0 M (2) 2.0 M (4) 0.75 M
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Day 29: Chemistry Regents Exam: January 2010 Part B-1. Continue. 46. Given the formula for an organic compound: H H H H O I
I
I
I
II
H – C – C – C – C – C – OH I
I
I
I
H H H H This compound is classified as an (1) aldehyde (2) amine
(3) ester (4) organic acid
47. Butanal and butanone have different chemical and physical properties primarily because of differences in their (1) functional groups (2) molecular masses (3) molecular formula (4) number of carbon atoms per molecule 48. Which salt is produced when sulfuric acid and calcium react completely? (1) CaH2 (3) CaS (2) CaO (4) CaSO4 49. Which radioisotope is used to treat thyroid disorders? (1) Co-60 (3) C-14 (2) I-131 (4) U-238
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189
Day 30: Chemistry Regents Exam: January 2010 Start: Answer all questions in Part B-2 and Part C before stopping
Part B-2:
Answer all questions in this part
Directions (51-65): Record your answers in the spaces provided in your answer booklet. Some questions may require the use of the Reference Tables for Physical Setting/Chemistry. 51. Based on Table G, determine the total mass of NH3 that must be dissolved in 200. grams of water to produce a saturated solution at 20.oC? [1] ______ g 52. Determine the total time that must elapse until ¼ of an original sample of the radioisotope Rn-222 remains unchanged. [1] ______ d Base your answers to questions 53 through 55 on the information below.
A phase change for carbon dioxide that occurs spontaneously at 20.oC and 1.0 atmosphere is represented by the balanced equation below. CO2(s)
+
energy ---- >
CO2(g)
53. Write the name of this phase change. [1] 54. Describe what happens to the potential energy of the CO2 molecules as this phase change occurs. [1]
55. Use the key to draw at least five molecules in the box to represent CO2 after this phase change is completed. [1]
Key = CO2 molecule
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Day 30: Chemistry Regents Exam: January 2010 Part B-2. Continue Base your answers to questions 61 through 63 on the information below.
The atomic and ionic radii for sodium and chlorine are shown in the table below. Atomic and Ionic Radii Particle
Radius(pm)
Na atom
190.
Na+ ion
102
Cl atom
97
Cl- ion
181
61. Write the ground state electron configuration for the ion that has a radius of 181 picometers. [1]
62. Convert the radius of an Na+ ion to meters. [1] ____ m 63. Explain, in terms of atomic structure, why the radius of an Na atom is larger than the radius of an Na+ ion. [1]
Base your answers to questions 64 through 65 on the information below.
The nucleus of one boron atom has five protons and four neutrons. 64. Determine the total number of electrons in the boron atom. [1]
65. Determine the total charge of the boron nucleus. [1]
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Day 30: Chemistry Regents Exam: January 2010 Part C Continue. Base your answer to questions 69 through 71 on the information below.
In a laboratory investigation, magnesium reacts with hydrochloric acid to produce hydrogen gas and magnesium chloride. The reaction is represented by the unbalanced equation below. Mg(s) +
HCl(aq) ---- > H2(g) +
MgCl2(aq)
69. State, in terms of the relative activity of elements, why this reactions is spontaneous. [1]
70. Balance the equation in your answer booklet, using the smallest whole-number coefficients. [1] ___Mg(s) +
__HCl(aq) ---- > __ H2(g) +
__MgCl2(aq)
71. Write a balance half-reaction equation for the oxidation that occurs. [1]
Base your answers to questions 72 through 75 on the information below.
An experiment is performed to determine how concentration affects the rate of reaction. In each of the four trials, equal volume of solution A and Solution B are mixed while temperature and pressure are held constant. The concentration of solution B is held constant, but the concentration of solution A is varied. The concentration of solution A and the time for the reaction to go to completion for each trial are recorded in the data table on the next page.
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Day 30: Chemistry Regents Exam: January 2010 Part C. Continue. Base your answers to questions 76 through 78 on the information below.
Carbon has three naturally occurring isotopes. C-12, C-13, and C-14. Diamonds and graphite are familiar forms of solid carbon. Diamond is one of the hardest substances known, while graphite is a very soft substance. Diamond has a rigid network of bonded atoms. Graphite has atoms bonded in thin layers that are held together by weak forces. Recent experiments have produced new forms of solid carbon called fullerenes. One fullerene, C60, is a spherical, cage-like molecule of carbon. 76. Determine both the total number of protons and the total number of neutrons in an atom of the naturally occurring carbon isotope with the largest mass. [1] Protons: _______ Neutrons: ______
77. Identify the type of bonding in a fullerene molecules. [1]
78. State, in terms of the arrangement of atoms, the difference between diamond and graphite. [1]
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Day 30: Regents Exam: Chemistry January 2010 Part C. Continue. Base your answer to questions 82 through 84 on the information below.
The diagram below shows a system in which water is being decomposed into oxygen gas and hydrogen gas. Litmus is used as an indicator in the water. The litmus turns red in test tube 1 and blue in test tube 2. The oxidation and reduction occurring in the test tubes are represented by the balanced equations below. Test tube 1: 2H2O(l) --- > O2(g) + 4H + 4eTest tube 2: 4H2O(l) + 4e- --- > 2H2(g) + 4OH-(aq)
82. Identify the information in the diagram that indicates this system is an electrolytic cell. [1]
83. Determine the change in oxidation number of oxygen during the reaction in test tube 1. [1] From _____ to
_______
84. Explain, in terms of the products formed in Test tube 2, why litmus turns blue in test tube 2. [1]
Day 30 Stop:
Correct your answers and note how many correct Points
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Answer Booklet: January 2010
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Answer Booklet: January 2010
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Day 30: Chemistry Regents Exam January 2010 Answers Part B-2 51) 112 g + 3 g 52) 7.64 d 53) Sublimation 54) The potential energy of the CO2 molecules increases The CO2(g) molecules have more potential energy than the CO2(s) molecules. 55)
Your diagram may vary (molecules should be spread out)
56)
57) Ag+ or Hg2+ or Pb2+ or silver ion or Lead(II) ion 58) Alkane
CnH2n+2
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Day 30: Chemistry Regents Exam January 2010 Answers Part C. 66) At STP, the intermolecular forces of I2 are stronger than F2. The intermolecular forces are weaker in F2. 67)
68) 0.5 g 69) Magnesium is more active than hydrogen. H2 is less active than Mg.. 70)
__Mg(s) + 2 HCl(aq) ----- > __H2(g) + ___MgCl2(aq)
71) Mg --- > Mg2+ + 2e72) As the concentration of A decreases, the rate of reaction decreases. As the concentration of solution A was decreased, the time for the reaction to finish increased.
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Day 30: Chemistry Regents Exam January 2010 Answers Part C
continues.
78) Diamond has atoms bonded strongly in three dimensional network. Diamond has a rigid network of bonded atoms. Graphite has atoms that are held weakly between layers. Graphite has atoms bonded in thin layers that are held together. by weak forces. 79) Combustion 80)
81)
144
Ba
or
144
Ba
or
Barium-144
or
Ba-144
56
82) A battery is part of the cell and is providing energy that causes the reaction. Electricity is used to operate the cell. 83) -2 to 0 84) Litmus turns blue when enough OH- ions is produced. The reaction in Test Tube 2 produces OH- ions that makes this solution basic. Litmus is blue in a basic solution
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Track Your Progress: Multiple Choice Questions How well have you been improving on the multiple choice questions? It’s easy to find out. Get the correct points that you noted at the end of each multiple choice questions set (Odd Days).
20 19
Plot the points on the graph below. You hope to see an upward trend on each graph.
18 17 16
15
15
14
14
13
13
12
12
10 Correct Points
10 9 8 Correct Points
Correct Points
11
7
9 8 7
6
6
5
5
4
4
3
3
2
2
1
1
0
0 1 3
5 7 9 Day
11 10 9 8 7 6 5 4 3 2 1
11 13 15 17 19 Day
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0
21 23 25 Day
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Reference Tables / Chemistry Table A: Standard Temperature and Pressure
Table B: Physical Constants for water
Table C: Selected Prefixes
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Reference Tables / Chemistry Table F: Solubility Guidelines
Table G: Solubility Curves
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Reference Tables / Chemistry Table I: Heat of Reactions at 101.3 kPa and 298 K
Table J Activity Series
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Reference Tables / Chemistry Table O: Symbols Used in Nuclear Chemistry
Table P: Organic Prefixes
Table Q: Homologous Series of Hydrocarbons
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