Chem question- electrochemistry

Question

Calculate E values for the following cells. Which reactions are spontanous as written (under standard conditions)? Balance the reactions that are not already balanced.

a. 2Ag (aq) Cu(s) <--> Cu^2 (aq) 2Ag(s)

b. Zn^2 (aq) Ni(s) <---> Ni^2(aq) Zn(s)

Answer 1

Ag+ + 1e- &gt;&gt; Ag  E° = + 0.800 V

Cu2+ + 2e- &gt;&gt; Cu  E° = + 0.337 V

Cu + 2 Ag+ &gt;&gt; Cu2+ + 2 Ag   E° = 0.800 - 0.337 =  0.463 V ( &gt; 0)

Zn2+ + 2e- &gt;&gt; Zn   E° =  - 0.763 V

Ni2+ + 2e- &gt;&gt; Ni   E° = - 0.257 V

Zn + Ni2+ &gt;&gt; Zn2+ + Ni   E° = + 0.763 - 0.257 = 0.506 V (&gt; 0)