Using standard reduction potentials, calculate the standard Ecell, emf, for each of the following reactions. State if each reaction is spontaneous or nonspontaneous. You must show the two half-reactions and balance the gain and loss of electrons.

a. H2(g) + I2(s) -> 2H^1+(aq) + 2I^1-(aq)

b. Ni^2+(aq) + 2Ce^5+(aq) -> Ni(s) + 2Ce^4+(aq)

c. 4Ce^3+(aq) -> Ce(s) + 3Ce^4+(aq) (Acid solution)

d. 2Al^3+(aq) + 3Cd(s) -> 2Al(s) + 3Cd^2+(aq)