APPENDICE B: Potentiels de réduction standards pour demi-réactions choisies E°red (V) 1,23 Demi-réaction O2(g) + 4H*(aq) + 4 e¯ → 2 H2O(1) Br2(1) + 2 e → 2 Br(aq) Ag*(aq) + e → Ag(s) Fe3+(aq) + e¯ → Fe²*(aq) Cu(OH)2(s) + 2 e¯ → Cu(s) + 2 OH(aq) 2H*(aq) + 2 e → H2(g) Pb2+ (aq) + 2 e → Pb(s) Ni2*(aq) + 2 e → Ni(s) Cd2*(aq) + 2 e → Cd(s) Fe2*(aq) + e¯ → Fe(s) 2 H20(1) + 2 e→ H2 + 2 OH(aq) Na*(aq) + e* → Na(s) [Zn(OH)4]²(aq) +2 e¯ → Zn(s) + 4 OH(aq) 1,09 0,80 0,77 0,34 0,00 -0,126 -0,26 -0,40 -0,45 -0,83 -2,71 -1,22
Zinc reacts with copper hydroxide by the following
Zn(s) + Cu(OH)2(s)----> [Zn(OH)4]2- (aq) + Cu(s)
a) Balance the reaction in a basic medium
b) Write down the two half reactions involved in this reaction, identifying the oxidation half reaction and the reduction half reaction. Using the data in Appendix B, find the standard oxidation and reduction potentials for each half reaction. Find the standard potential, E0reaction, of the global reaction
Oxidation half reaction: E0OX=
Half reduction reaction: E0RED=
E0 reaction:
c) A stack is built using components of this reaction. Calculate the potential, Epile, of the battery at 25°C if the concentration of [Zn (OH)4]2-(aq) was 0.10 M and the pH of the solution was 12? (Hint: use the Nernst equation)
Step by step
Solved in 2 steps with 2 images