6. A cell has been set up as shown in the following diagram, and E°has been measured as
   1.00 V at 25°C. Calculate ∆G°for the reaction.

A. −386 kJ

B. −193 kJ

C. 1.00 kJ

D. 193 kJ

E. 386 kJ

Answer: B

The formula you need for this problem is ∆G°= −nFE°. The Faraday constant, F, is equal to

9.65 × 104 joules ⋅volt–1⋅mole–1⋅ nis the number of electrons transferred between oxidizing

and reducing agents in a balanced redox equation.

Step 1:Write the balanced redox equation.

Zn(s) + Cu2+(aq) →Zn2+(aq) + Cu(s)

Step 2:Identify the variables needed for the equation.

∆G°=? F= 9.65 x 10^4 joules ⋅volt–1⋅mole–1

n= 2 E°= 1.00 volt

Step 3:Substitute into the equation and solve.

..
G

moles e

volt mole e

joules volt

∆ 1

(^2) 965 10
1
(^4100)

:

%=- #

`j

= −1.93 × 105 joules = −193 kJ

flow of electrons

.85v

salt bridge

Zn Cu

1.00 M Zn(NO 3 ) 2 1.00 M Cu(NO 3 ) 2

Reduction and Oxidation