Redox Reactions...Help Please..Need Answer Tonight!?

Question

A couple of problems I couldn't get on my homework. Any help appreciated!!

Write rxn like this: Ox(1) + Red(2) + other -> Red(1) + Ox(2) + other

1. Write net equation for the spontaneous redox reaction and determine the standard cell potential that results when each of the following redox couples are connected in an electrochemical cell.

a. H1+/H2 and Cu2+/Cu E˚ =
b. Cr/Cr3+ and Ag1+/Ag E˚ =

2. Write net equations for the spontaneous redox reactions that occur during the following:

A copper wire is added to nitric acid

Link to table of standard reduction potentials: http://www.webassign.net/wertz/caqs/html/resource/redox.html

Answer 1

Your provided link to table of standard reduction potentials is not accessible to me. It popped up a message of "We're sorry. You do not have access to this page."
To solve this kind of problem, always remember to balance the charge. When you have the standard reduction potentials given, life becomes quite easy. You first find the two relevant equations of half reaction. Time each equation with appropriate integer parameters to make the coefficient of the charge (e-) the same. Then you reverse the direction of the reaction with lower potential (also change the sign of that potential at the same time), and adding the two resulted equations together (also adding the potentials at the same time). Finally cancel the identical charges from both sides of the reaction equation.

a. H1+/H2 and Cu2+/Cu E˚ =
2H+ + Cu = H2 + Cu(2+)

b. Cr/Cr3+ and Ag1+/Ag E˚ =
3Ag+ + Cr = 3Ag + Cr(3+)

These are the net ionic equations. You may add spectators to each equation. For example:
a) H2SO4 + Cu = H2 + CuSO4
b) 3AgNO3 + Cr = 3Ag + Cr(NO3)3