What is the electrode potential for Cu2+/Cu+?

Question

What is the electrode potential for Cu2+/Cu+?

Cu+ + e- = Cu + 0.521V
Cu2+ +2e- = Cu + 0.377V

Answer 1

You practically need the standard potential for the reaction
Cu2+ +e <=> Cu+

Cu(2+) +2e <=> Cu E1=+0.377 V (1)

Cu(+) + e <=> Cu E2=+0.521 V. Invert and you get
Cu <=> Cu(+) +e E'2= -0.521 V (2)

Add (1) and (2) and you get

Cu(2+) +2e +Cu <=> Cu +Cu(+) +e E=E1+E'2 =>

Cu(2+) +e <=> Cu(+) E=0.377+(-0.521) = -0.144 V