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Unformatted text preview: moore (jwm2685) Homework 7 vanden bout (51640) 1 This printout should have 29 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points Using the set of smallest possible integer co efficients to balance the redox equation ClO 3 + I 2 IO 3 + Cl (acidic solution), the coefficient for I 2 is 1. 3. correct 2. 1. 3. 2. 4. The correct coefficient is not given. 5. 4. Explanation: The oxidation number of Cl changes from +5 to 1, so Cl is reduced. The oxidation number of I changes from 0 to +5, so I is oxidized. We set up oxidation and reduction halfreactions: Red: ClO 3 Cl Oxid: I 2 IO 3 Cl atoms are balanced. We need 2 IO 3 molecules to balance I: Oxid: I 2 2 IO 3 Since this is an acidic solution, we use H 2 O and H + to balance O and H atoms, adding the H 2 O to the side needing oxygen: Red: 6 H + + ClO 3 Cl + 3 H 2 O Oxid: 6 H 2 O + I 2 2 IO 3 + 12 H + We balance the total charge in each half reaction by adding electrons. In the preceding reduction reaction there is a total charge of +5 on the left and 1 on the right. Six elec trons are added to the left: Red: 6 e + 6 H + + ClO 3 Cl + 3 H 2 O Oxid: 6 H 2 O + I 2 2 IO 3 + 12 H + + 10 e The number of electrons gained by Cl must equal the number of electrons lost by I. We multiply the reduction reaction by 5 and the oxidation reaction by 3 to balance the elec trons: Red: 30 e + 30 H + + 5 ClO 3 5 Cl + 15 H 2 O Oxid: 18 H 2 O + 3 I 2 6 IO 3 + 36 H + + 30 e Adding the halfreactions gives 18 H 2 O + 3 I 2 + 30 H + + 5 ClO 3 6 IO 3 + 36 H + + 5 Cl + 15 H 2 O Canceling like terms gives the overall bal anced equation 3 H 2 O + 3 I 2 + 5 ClO 3 6 IO 3 + 6 H + + 5 Cl 002 10.0 points How many electrons are required to balance the half reaction below? H + + ClO + e  Cl + H 2 O 1. 3 2. 1 3. 2 correct 4. 4 Explanation: Each chlorine atom undergoes a change of oxidation state from +1 to 1. This is there fore a 2 electron process. 003 10.0 points Consider the reaction Zn(s) + OH (aq) + H 2 O( ) + NO 3 (aq) Zn(OH) 2 4 (aq) + NH 3 (g) If the coefficient of NO 3 in the balanced equation is 1, how many electrons are trans ferred in the reaction? 1. 8 correct 2. 6 3. 2 4. 10 5. 4 Explanation: moore (jwm2685) Homework 7 vanden bout (51640) 2 004 10.0 points In the reaction 2 MnO 4 + 16 H + + 10 I 2 Mn 2+ + 8 H 2 O + 5 I 2 of permanganate anion with iodide in acidic solution, what has been reduced and what is the change in oxidation number?...
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 Spring '07
 Holcombe
 Chemistry

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