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Chemistry 1st Semester Exam 2013-2014 Multiple Choice Identify the choice that best completes the statement or answers the question. All questions have the same value unless noted. 1. All of the following precautions should be taken before lighting a Bunsen burner EXCEPT: a. long hair and loose clothing should be c. know the locations of safety equipment tied back or rolled up. (i.e. fire blankets, etc.) b. safety goggles properly worn. d. make sure the instructor is not in the room A student conducts an experiment to determine the effect of adding salt on the boiling temperature of water. The results are shown below. Sample Amount of Salt Boiling Temperature Sample 1 0g 100.0° C Sample 2 2g 102.3° C Sample 3 5g 104.8° C Sample 4 10 g 107.5° C 2. Which is the independent variable in this experiment? a. Amount of salt added c. Boiling temperature b. Volume of water d. Time required for water to boil 3. Which is a value that should remain constant for all samples in this experiment? a. Amount of salt added c. Boiling temperature b. Volume of water d. Time required for water to boil 4. Which is the control in this experiment? a. Sample 1 b. Sample 2

c. d.

Sample 3 Sample 4

5. Which is a reasonable hypothesis for this experiment? a. If salt is added to water, the water will boil at a higher temperature b. Salt makes water boil c. If water is boiling, it must have salt added to it d. If salt is added to water, the water will get cloudy 6. Calculate the following temperature(s) using this equation: K = °C + 273 Convert 20 °C to K a. -253 b. 0 c. 293 d. 253

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7. The conversion of 2.1 kg to mg is a. 2.1 x 10-6 b. not possible

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c. d.

2.1 2.1 x 106

8. The accepted value is 15.63. Which correctly describes this student’s experimental data? Trial Measurement 1 12.84 2 13.02 3 12.96 a. b.

precise but not accurate both accurate and precise

c. d.

accurate but not precise neither accurate nor precise

9. Give the proper reading indicated by the thermometer below.

a. b.

10.6 oC 16.6 oC

c. d.

16.0 oC 16.1 oC

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10. Which of the following substances is an element? a. Baking soda c. b. Iron d.

Salt Sugar

11. Using the periodic table, determine the atomic number for aluminum. a. 13 c. 26.98 b. 14 d. 26.9815 12. An atom of carbon has 6 protons, 6 neutrons and 6 electrons. Which diagram represents a carbon atom?

a.

c.

b.

d.

Use the diagram below for the next two questions.

Figure 6-2 13. What is the nucleus of the atom made of? a. I only b. III only

c.

II and III

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d.

I and III

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Use the following graph for the next questions.

14. The element having an atomic radius closest to 25 picometers is number a. 1 c. 3 b. 2 d. 10 15. Using the graph above, what happens to the atomic radii of elements as you go down a column in the periodic table? a. it decreases c. it increases b. it increases then decreases d. there is no relationship Use the graph below to answer the next questions.

16. According to the data in the graph above, the general trend of electronegativity is a. decreasing as one goes across a period. c. decreasing as one goes up a group. b. increasing as one goes down a group. d. decreasing as one goes down a group.

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17. Which of the following is the most probable electronegativity of element #14 in the graph above? a. 1.3 c. 1.9 b. 1.6 d. 2.2 18. What is the element that is an alkali metal, likes to have a +1 charge and is in the third period? a. Li c. Na b. Cl d. S 19. Which of the following categories includes the majority of the elements? a. metals c. nonmetals b. liquids d. metalloids 20. How many atoms of fluorine are in a molecule of carbon tetrafluoride, CF4? a. 1 c. 4 b. 2 d. 5 21. What is the formula for the compound formed by calcium ions, Ca 2+, and chloride ions, Cl –? a. CaCl c. CaCl3 b. Ca2Cl d. CaCl2 22. Which is the charge that results when oxygen becomes an ion? a. +2 c. +3 b. -3 d. -2 23. Which is the correct name for the compound Na 3P? a. Sodium Phosphide c. Sodium Phosphate b. Sodium Phosphite d. Sodium (III) Phosphide 24. What is the total charge of any ionic compound? a. 0 c. b. 1 d.

8 -1

25. What type of ions do metals form? a. cations because they gain electrons b. anions because they gain electrons c. cations because they lose electrons d. anions because they lose electrons 26. The name that matches the element symbol, S, is a. sodium. b. sulfur. c. hydrogen. d. helium. 27. The electron in a hydrogen atom has its lowest total energy when the electron is in its a. neutral state. c. ground state. b. excited state. d. quantum state.

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28. Which is the ground-state electron configuration for an atom with 12 electrons? a. 1s22s22p63s23p1 c. 1s22s22p63s2 2 2 6 1 1 b. 1s 2s 2p 3s 3p d. 1s22s22p8 29. The electron configuration of nitrogen is 1s22s22p3. How many more electrons does nitrogen need to have an electron configuration similar to neon? a. 1 c. 5 b. 3 d. 8 30. Almost all of the mass of an atom is determined by a. protons and electrons. b. protons and neutrons. c. electrons and neutrons. d. electrons and positrons. 31. Below is the particle composition of four different atoms. Atom Protons Neutrons Electrons W 1 0 1 X 11 11 10 Y 17 17 18 Z 12 13 12 Which of these is negatively charged ion? a. W b. X c. Y d. Z

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32. The table below shows how the electrons are arranged in the atoms of four different elements: J, L, M, Q. Electron arrangement in sample atoms Number of electrons Element Element Element Element J L M Q First 2 2 2 2 energy level Second 8 8 8 8 energy level Third 1 16 7 8 energy level Which element is likely to be a good conductor of electricity? a. Element J b. Element L c. Element M d. Element Q 33. The following diagram shows a portion of the periodic table of the elements. Information from partial periodic table of the elements 3A 4A 5A 6A 7A 8A B C N O F Ne Al Si P S Cl Ar Ga Ge As Se Br Kr Which two elements have similar chemical properties? a. Ga and Si b. P and S c. Ne and O d. Cl and Br 34. Which statement best describes why argon is located in the last column on the periodic table? a. Argon has a full outer shell of electrons. b. Argon has a large atomic radius for its period. c. Argon is a gas at room temperature. d. Argon is a very reactive element.

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The diagram below shows the electronegativity of different elements on the periodic table.

35. Compared to other periodic table elements, an atom of fluorine (F) is most likely to do which of the following? a. Form an ion that has a charge of +1. b. Bond with sodium by donating one of its electrons to sodium. c. Form an ion that has a charge of +2. d. Bond with sodium by capturing one of sodium's outer electrons. 36. Answering which of the following questions would BEST help a student determine whether an element is a transition element? a. Is the element a metal or a nonmetal? b. Is the element reactive or nonreactive? c. What is the element’s atomic electron configuration? d. What are the element’s most common oxidation states? 37. Which of the following correctly lists elements from the smallest atomic radius to the largest atomic radius? a. Fluorine, bromine, iodine b. Iodine, bromine, fluorine c. Bromine, fluorine, neon d. Iodine, fluorine, bromine

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38. ATOMIC RADII OF GROUP 2 ELEMENTS Atom Atomic Radius (in nm) Be 0.111 Mg 0.160 Ca 0.197 Sr 0.210 Ba 0.217 Ra 0.220 The increase in the atomic radii of the elements in this table can best be explained by the a. addition of electrons to the same principle energy level which causes increased shielding of electrons. b. increase in the number of electrons being added to the 2s-sublevel and shrinking of the s-orbitals. c. addition of electrons to increasingly higher principle energy levels and increased electron shielding. d. increase in the nuclear charge as more electrons are added to successively higher principle energy levels. 39. The table gives the atomic number and average atomic mass for cobalt. Atomic number 27 Average atomic mass 58.93 Based on this information, MOST cobalt atoms have a total of how many neutrons? a. 27 b. 31 c. 32 d. 59 40. Which of the following statements best summarizes the modern quantum mechanical model of the atom? a. Electrons travel in circular paths around a charged nucleus. b. Negative electrons are found in positive matter. c. Matter is composed of identical and indivisible particles. d. Electrons are likely to be found in orbitals around the nucleus.

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Hydrogen gas (H2) can be produced through many different processes. Students performed the following experiments to study how H2 forms. Experiment 1 An Erlenmeyer flask was filled with 100 mL of 1 M hydrochloric acid (HCl). A 0.327g sample of zinc (Zn) was placed inside a balloon. The balloon was then fitted over the top of the flask, forming an airtight seal, as shown in Figure 1.

The zinc was allowed to drop into the HCl, a reaction took place, forming H2 gas that caused the balloon to expand. The gas in the balloon was allowed to adjust to room temperature and pressure, and the final volume of the gas was recorded. The remaining zinc, if any, was weighed. The procedure was repeated with different volumes of HCl and masses of Zn. The results were recorded in Table 1. Table 1 Trial Initial Initial Final Final volume HCl mass * volume mass Zn (mL) Zn (g) H2 (mL) (g) 1 100 0.327 112 0.000 2 100 0.654 112 0.327 3 100 0.981 112 0.654 4 50 0.654 56 0.491 5 200 0.654 224 0.000 6 300 0.654 224 0.000 7 400 0.654 224 0.000 *Note: Zn has a molar mass of 65.4 g/mol. Based on the data obtained in the experiment, the following equation was suggested for the reaction: 2HCl + Zn → ZnCl2+ H2 Experiment 2 Two zinc electrodes were mounted vertically in a glass beaker, as shown in Figure 2.

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The beaker was then filled with enough deionized H2O so that the electrodes were completely submerged. Test tubes filled with H2O were placed over each of the electrodes. Insulated wires were then connected between each electrode and opposite ends of a battery. A reaction took place, forming bubbles of gas at each electrode. The battery was then disconnected and the test tubes were removed from the apparatus. The final volume of gas in each test tube was recorded. It was determined that 1 molecule of H2 gas was produced for every H2O reacted: 2 H2O → 2 H2 + O2 41. Which of the following best represents the relationship between the final volume H2 and the initial volume of HCI in trials 4-6 of Experiment 1?

a.

c.

b.

d.

42. Which of the following was not directly manipulated or controlled by the student in Experiment 1? a. The initial mass of Zn b. The initial volume of HCl c. The flask and balloon setup d. The final volume of H2 43. In Experiment 2, why did the students use deionized water? a. Ions in the water could interfere with the desired reaction. b. Ions in the water could electrocute the students. c. Deionized water prevents the electrodes from heating. d. Deionized water doesn't contain hydrogen. 11 of 12

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44. In Experiment 2, what is the ratio of the number of O2 molecules produced to the number of H2 molecules produced in the test tubes? a. 1:1 b. 1:2 c. 2:1 d. 4:1 45. Calcium chloride CaCl2 and potassium chloride, KCl are both ionic compounds with no net electrical charge. Why do the chemical formulas for these two compounds have different numbers of chlorine atoms? a. Calcium has more protons than potassium. b. Calcium reacts better with chlorine. c. The charge of a chloride ion varies depending on the cation to which it bonds. d. The charge of the cation in each of these compounds is different. Essay 46. Use the OEA style of writing for your response to the following question. Scientists examined three unknown elements and determined that all three elements have four electrons in their outermost energy level. Determine which group the three elements belong to and justify your answer. You may use the information in the periodic table.

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