Chemistry

Answers to Chapter 18 Study Questions

 

1. a) -3; [x + 3(1) = 0] b) 0 c) +4; [x +2(-2) = 0] d) +5; [x + 3(-2) = -1]

 

2. a) Br2 b) I c) Br d) Br2 e) I-

 

3. a) left: Li = 0, Cu2+ = +2; right: Li+ = +1, Cu = 0

ox: [Li Li+ + e-] x 2; red: Cu2+ + 2 e- Cu

balanced: 2 Li(s) + Cu2+(aq) 2 Li+(aq) + Cu(s)

b) left: Ni = 0, Mn = +7, O = -2; right: Ni2+ = +2, Mn2+ = +2

ox: [Ni(s) Ni2+ + 2 e-] x 5; red: [5 e- + 8 H+ + MnO4- Mn2+ + 4 H2O] x 2

balanced: 5 Ni(s) + 16 H+(aq) + 2 MnO4-(aq) 5 Ni2+(aq) + 2 Mn2+(aq) + 8 H2O

c) left: Mn2+ = +2, N = +5, O = -2; right: Mn = +4, O = -2, N = +2

ox: [2 H2O + Mn2+ MnO2 + 4 H+ + 2 e-] x 3

red: [3 e- + 4 H+ + NO3- NO + 2 H2O] x 2

balanced: 2 H2O + 3 Mn2+(aq) + 2 NO3-(aq) 3 MnO2(s) + 4 H+(aq) + 2 NO(g)

 

4. a) Al is oxidized. Pb is reduced

b) ox: Al Al3+ + 3 e-; red: Pb2+ + 2 e- Pb

c) 2 Al(s) + 3 Pb2+(aq) 2 Al3+(aq) + 3 Pb(s)

 


d) e) lead (Pb); since Pb2+ Pb