Problem: Calculate Eº cell for each of the following balanced redox reactions.Determine whether the reaction is spontaneous as written.a. 2Cu(s) +Mn2+(aq) → 2Cu+(aq) + Mn(s)b. MnO2(s) + 4H+(aq) + Zn(s) → Mn2+(aq) + 2H2O(l) + Zn2+(aq)c. Cl2(g) + 2F−(aq) → F2(g) + 2Cl−(aq)

$\boxed{\mathbf{E}{\mathbf{°}}_{\mathbf{cell}}\mathbf{=}\mathbf{E}{\mathbf{°}}_{\mathbf{cathode}}\mathbf{-}\mathbf{E}{\mathbf{°}}_{\mathbf{anode}}}$  

Recall:

Lose               Gain
Electron         Electrons
Oxidation       Reduction

cathode → reduction → oxidation number decreases

anode → oxidation → oxidation number increases

For ions: charge of the ion = oxidation number
For neutral atoms/compound: oxidation number = 0

Also recall:

E°_cell > 0 → spontaneous in the forward direction
E°_cell < 0 → nonspontaneous in the forward direction