Problem: Which of the following changes will increase the voltage of the cell Al(s)|Al3+ (aq, 1.00 M)||Cu2+ (aq, 1.00 M)|Cu(s)?I. Increasing the surface area of the Al electrodeII. Decreasing the concentration of Al3+(aq) to 0.001 MIII. Decreasing the concentration of Cu2+(aq) to 0.001 Ma. I and IIb. II and IIIc. II onlyd. III onlye. I only

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We are being asked to determine which change will result to increase the voltage of the cell:

Al(s) | Al3+(aq, 1.00 M) || Cu2+(aq,1.00 M) | Cu(s)

 In the Nernst Equation, we will calculate for Q where Q is equal to [products]/[reactants].

The Nernst Equation at 25°C:

Rewrite the Nernst Equation:

Ecell=E°cell-(0.05916 Vn) log Q

Ecell = cell potential under non-standard conditions
cell = standard cell potential
n = number of e- transferred
Q= reaction quotient = [products]/[reactants] 


We have to write the overall reaction and determine the products and reactants:

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Problem Details

Which of the following changes will increase the voltage of the cell Al(s)|Al3+ (aq, 1.00 M)||Cu2+ (aq, 1.00 M)|Cu(s)?

I. Increasing the surface area of the Al electrode

II. Decreasing the concentration of Al3+(aq) to 0.001 M

III. Decreasing the concentration of Cu2+(aq) to 0.001 M

a. I and II
b. II and III
c. II only
d. III only
e. I only