Review Sheets for Chapter 20. 1 1. Assuming the following reaction proceeds in the forward direction, 3 Sn4+(aq) + 2 Cr(s) ? 3 Sn2+(aq) + 2 Cr3+(aq) 4+ a. Sn (aq) is the reducing agent and Cr(s) is the oxidizing agent. b. Cr(s) is the reducing agent and Sn2+(aq) is the oxidizing agent. c. Sn4+(aq) is the reducing agent and Sn2+(aq) is the oxidizing agent. d. Cr(s) is the reducing agent and Cr3+(aq) is the oxidizing agent. e. Cr(s) is the reducing agent and Sn4+(aq) is the oxidizing agent. 2. The following reaction occurs spontaneously. H+(aq) + Ca(s) ? Ca2+(aq) + H2(g) Write the balanced oxidation half-reaction. a. 2 H+(aq) + 2 e– ? H2(g) b. 2 H+(aq) ? H2(g) + 2 e– c. H2(g) ? 2 H+(aq) + 2 e– d. Ca(s) + 2 e– ? Ca2+(aq) e. Ca(s) ? Ca2+(aq) + 2 e– 3. Write a balanced half-reaction for the reduction of CrO42–(aq) to Cr(OH)3(s) in a basic solution. a. CrO42–(aq) + 3 OH–(aq) + 3 e– ? Cr(OH)3(s) + 2 O2(g) b. CrO42–(aq) + 3 H+(aq) + 3 e– ? Cr(OH)3(s) c. CrO42–(aq) + 3 H+(aq) ? Cr(OH)3(s) + 2 e– d. CrO42–(aq) + 4 H2O( ) + 3 e– ? Cr(OH)3(s) + 5 OH–(aq) e.
CrO42–(aq) + 3 OH–(aq) ? Cr(OH)3(s) + 2 O2(g) 4. Write a balanced chemical equation for the oxidation of Cd(s) by concentrated nitric acid, producing NO2(g) and Cd2+(aq). a. HNO3(aq) + Cd(s) ? Cd2+(aq) + NO2(g) + OH–(aq) b. 2 HNO3(aq) + Cd(s) ? Cd2+(aq) + 2 NO2(g) + 2 OH–(aq) c. HNO3(aq) + Cd(s) + H+(aq) ? Cd2+(aq) + NO2(g) + H2O( ) d. 4 HNO3(aq) + Cd(s) ? Cd2+(aq) + 2 NO2(g) + 2H2O( ) + 2 NO3–(aq) e. HNO3(aq) + Cd(s) ? Cd2+(aq) + NO2(g) Answer Section MULTIPLE CHOICE 1. 2. 3. 4. ANS: ANS: ANS: ANS: E E D D
