Chemistry I Accelerated Study Guideline - Chapter Twenty Oxidation–Reduction Reactions _____________________________________________________________________________________________________________________
By the end of this chapter the skills you should be able to demonstrate are: 1. Define oxidation and reduction in terms of the loss or gain of oxygen or hydrogen. 2. Identify the oxidized and reduced species in oxidation-reduction reaction. 3. List the characteristics of an oxidation-reduction reaction. 4. Compute oxidation numbers for atoms in compounds. 5. Analyze a reaction to determine if it is an oxidation-reduction reaction. 6. Apply the half-reaction method to balance redox reactions. Suggested Problems: p.657-659 #30, 38(c,d,e), 39, 47, 52, 53, 55, 56, 59, 62, 63, 64, 65
ChemIAcc-20REDOX WS
Dr. Corell - Chemistry I Accelerated
TV Ontario – Electrochemistry Video (Parts 1 + 2) 1. What do all batteries have in common? 2. Why is the Na+ considered oxidized even though no oxygen is involved? 3. What is reduction? 4. Why are oxidation-reduction reactions redox? 5. How many electrodes does a battery contain? 6. What happens at the negative electrode? What is the negative electrode called? 7. Why does copper take electrons away from zinc? 8. What causes the blue color in the Copper(II) sulfate solution? 9. What is the “pecking order” of ions called?
Assigning Oxidation Numbers – Practice Problems For each of the following compounds assign the oxidation number for each element 1.
Sulfuric Acid
2.
Barium Flouride
3.
Sulfur Trioxide
4.
Phosphoric Acid
5.
Tetraphosphorus Hexaoxide
6.
Potassium Manganate
7.
Calcium Dihydrogen Phosphate
8.
Boron Hydroxide
9.
Ammonia
10.
Cobalt(II) Hydroxide
11.
Iron(III) Chloride
12.
Magnesium Nitride
13.
Sodium Phosphate
14.
Barium Sulfate
15.
Zinc Carbonate
16.
Boric Acid
page 2
ChemIAcc-20REDOX WS
Dr. Corell - Chemistry I Accelerated
17.
Sulfur Dichloride
18.
Chromium(III) Chloride
19.
Mercury(II) Sulfate
20.
Dinitrogen Pentoxide
21.
H2S2O7
22.
HAuCl4
23.
Ca2Sb2O7
24.
Mg(BF4)2
In the following reactions, identify which element is oxidized and which is reduced; then balance. 1.
Hydrogen plus chlorine in a synthesis reaction
2.
Carbon plus water produces Carbon monoxide plus hydrogen gas
3.
Silicon dioxide plus carbon produces Silicon plus carbon monoxide
4.
Zinc plus sulfuric acid in a single replacement reaction
In the following reactions, identify which element is oxidizing agent and which is the reducing agent; then balance. 1.
Carbon plus Chlorine produces Carbon Tetrachloride
2.
Phosphorus plus Chlorine in a synthesis reaction
3.
Lead plus hydrochloric acid produces Lead(II) chloride plus hydrogen gas
4.
Carbon Dioxide plus Magnesium produces Carbon plus Magnesium oxide
5.
Potassium Dichromate plus Hydrogen Iodide produces Potassium Iodide plus Chromium(III) Iodide plus Iodine gas plus water
page 3
ChemIAcc-20REDOX WS
Dr. Corell - Chemistry I Accelerated
6.
Copper plus Silver Nitrate produces Copper(II) Nitrate plus Silver
7.
Sodium Sulfate plus Carbon produces Carbon monoxide plus Sodium Sulfide
On the line at the left, write the letter of the description that best matches each term _____ 1. oxidation
a. the substance that accepts electrons from another substance
_____ 2. reduction
b. a process by which electrons are transferred between reactants
_____ 3. oxidizing agent
c. the charge that an atom in a compound would have if the electrons belonged to the more electronegative atom.
_____ 4. reducing agent
d. the process by which a substance loses one or more electrons
_____ 5. redox reaction
e. the substance that undergoes oxidation
_____ 6. oxidation number
f. the process by which a substance gains one or more electrons
Complete the following in the space provided 1. The oxidation number of an free, neutral element is ________________. 2. The oxidation number of a monatomic ion is ________________. 3. Elements in group 1 of the periodic table have an oxidation number of _______________. 4. Elements in group 2 of the periodic table have an oxidation number of _______________. 5. In most compounds, aluminum has an oxidation number of _______________. 6. Fluoride has an oxidation number of _______________. 7. Hydrogen has an oxidation number of _______________ when combined with non-metals. 8. Oxygen has an oxidation number of _______________ in most compounds and ions. 9. The sum of individual oxidation numbers of all atoms in a formula for a compound is ___________. 10. The sum of individual oxidation numbers of all atoms in a formula for a polyatomic ion is equal to ____________________.
Answer each of the following in the space provided 1. What are some characteristics of a strong oxidizing agent? Give an example.
2. What are some characteristics of a strong reducing agent? Give an example.
3. Can a substance be oxidized without another being reduced? Why or why not? page 4
ChemIAcc-20REDOX WS
Dr. Corell - Chemistry I Accelerated
4. What are the definitions of oxidation and reduction? a. in terms of electrons b. in terms of oxygen atoms c. in terms of oxidation number
Follow the steps in the following reactions to balance the reactions using the halfreaction method 1. Aqueous nitrous acid plus aqueous hydroiodic acid yields nitrogen monoxide gas plus solid iodine. a. Write the unbalanced formula equations
b. The element oxidized is ____________. d. Write the balanced oxidation half-reaction
c. The element reduced is _____________.
e. Write the balanced reduction half-reaction
f. Write the net-ionic equation
g. Write the complete balanced equation
2. Solid Copper plus aqueous nitric acid yields aqueous Copper(II) nitrate plus nitrogen dioxide gas plus liquid water. a. Write the unbalanced formula equations
b. The element oxidized is ____________. d. Write the balanced oxidation half-reaction
c. The element reduced is _____________.
e. Write the balanced reduction half-reaction
f. Write the net-ionic equation
g. Write the complete balanced equation page 5
ChemIAcc-20REDOX WS
Dr. Corell - Chemistry I Accelerated
3. Solid Tetrarsenic hexaoxide plus chlorine gas plus liquid water yields aqueous Arseneic acid (H3AsO4) plus aqueous hydrochloric acid. a. Write the unbalanced formula equations
b. The element oxidized is ____________. d. Write the balanced oxidation half-reaction
c. The element reduced is _____________.
e. Write the balanced reduction half-reaction
f. Write the net-ionic equation
g. Write the complete balanced equation
4. Solid Phosphorus (P4) plus liquid water yields aqueous Pyrophosphorus acid (H2PO2) plus Phosphorus trihydride gas. a. Write the unbalanced formula equations
b. The element oxidized is ____________. d. Write the balanced oxidation half-reaction
c. The element reduced is _____________.
e. Write the balanced reduction half-reaction
f. Write the net-ionic equation
g. Write the complete balanced equation
page 6
ChemIAcc-20REDOX WS
Dr. Corell - Chemistry I Accelerated
5. Laughing gas (dintrogen monoxide) plus aqueous bleach (sodium hypochlorite) yields aqueous sodium chloride plus aqueous sodium nitrite. Note: This is in basic solution. a. Write the unbalanced formula equations
b. The element oxidized is ____________. d. Write the balanced oxidation half-reaction
c. The element reduced is _____________.
e. Write the balanced reduction half-reaction
f. Write the net-ionic equation
g. Write the complete balanced equation
Challenge Problems 1. Aqueous Sodium Permanganate plus Hydrochloric Acid yields Chlorine gas plus aqueous Mangenese(II) Chloride. Hint: There is another compound that is needed to balance the reaction but it is only made of spectator ions and you need to figure that out as you solve the problem. a. Write the unbalanced formula equations
b. The element oxidized is ____________. d. Write the balanced oxidation half-reaction
c. The element reduced is _____________.
e. Write the balanced reduction half-reaction
f. Write the net-ionic equation
g. Write the complete balanced equation page 7
ChemIAcc-20REDOX WS
Dr. Corell - Chemistry I Accelerated
2. Aqueous Sodium Chromate plus aqueous Hydrochloric Acid yields aqueous Chlorous acid plus aqueous Chromium(III) Chloride. Hint: There is another compounds that are needed to balance the reaction and you need to figure them out as you solve the problem. a. Write the unbalanced formula equations
b. The element oxidized is ____________. d. Write the balanced oxidation half-reaction
d. The element reduced is _____________.
e. Write the balanced reduction half-reaction
f. Write the net-ionic equation
g. Write the complete balanced equation
3. Aqueous Sodium Hydroxide plus aqueous Calcium Hydroxide plus solid Carbon plus Chlorine dioxide gas yields aqueous Sodium Chlorite plus solid calcium carbonate plus liquid water. (Note: The reaction takes place in basic solution) a. Write the unbalanced formula equations
b. The element oxidized is ____________. d. Write the balanced oxidation half-reaction
d. The element reduced is _____________.
e. Write the balanced reduction half-reaction
f. Write the net-ionic equation
g. Write the complete balanced equation page 8
ChemIAcc-20REDOX WS
Dr. Corell - Chemistry I Accelerated
4. Aqueous Sodium Permanganate plus solid Zinc plus liquid water yields solid Manganese Dioxide plus solid Zinc Hydroxide. (Note: The reaction takes place in basic solution) a. Write the unbalanced formula equations
b. The element oxidized is ____________. d. Write the balanced oxidation half-reaction
d. The element reduced is _____________.
e. Write the balanced reduction half-reaction
f. Write the net-ionic equation
g. Write the complete balanced equation
Word Puzzles In the United Kingdom these puzzles are called DINGBATS. For example: What is the element, UALUMM? Ans: ALUM in (between) UM = ALUMINUM.
