Question

# Calculate the non standard Gibbs Free Energy change, ΔG at 250C for the following reaction with...

Calculate the non standard Gibbs Free Energy change, ΔG at 250C for the following reaction with the indicated concentrations.

Zn + 2Ag+ (0.30M) → 2Ag + Zn2+ (0.50M)

Remember you'll need to calculate both the standard and non standard cell potential Ecell.

Remember ΔG0 = − nFE0cell  and a similar equation for the NONstandard value ΔG = −nFEcell

Here are the standard reduction potentials:

Zn2+/ Zn: - 0.763V
Ag+/ Ag: + 0.799V

Answer in kJ to 3SF including signs as needed

Part 2

Calculate the value of lnK where K is the equilibrium constant at 250C for the following reaction with the indicated concentrations.

Zn + 2Ag+ (0.30M) → 2Ag + Zn2+ (0.50M)

You should have already calculated both the standard and non standard cell potentials.

Remember ΔG0 = − nFE0cell  and ΔG0 = - RTlnK

You must use the standard value of ΔG to find K!!!

Think about what value of Ecell you need to use!!

Zn + 2Ag+ (0.30M) ----> 2Ag + Zn2+ (0.50M)

E0cell = Ecathode - E0anode

= 0.799 -(-0.763)

= 1.562 v

DG0 = -nFE0cell

= -2*96500*1.562

= -301.5 kj

= -3.01*10^2 kj

Ecell = E0cell- (0.0591/n)log([Zn2+]/[Ag+]^2

= 1.562-(0.0591/2)log(0.5/0.3^2)

= 1.54 v

DG = - nFEcell

= -2*96500*1.54

= -297.22 kj

= -2.97*10^2 kj

part 2

DG0   = -3.01*10^2 kj

DG0 = - RTlnK

-3.01*10^5 = -8.314*298lnK

lnK = 121.5

K = 5.79*10^52