Consider the following half-reactions:

What is the for the following redox equation?

Question

Consider the following half-reactions:

What is the for the following redox equation?

Quizplus · Accepted Answer

To find the cell potential (E°cell) of the given redox equation, we need to subtract the reduction potential of the half-reaction that is being oxidized from the reduction potential of the half-reaction that is being reduced.

The reduction half-reaction is: 
Zn^2+ + 2e^- --> Zn (E° = -0.76 V)

The oxidation half-reaction is: 
Pb --> Pb^2+ + 2e^- (E° = -0.13 V)

To calculate the overall reaction, we need to flip the oxidation half-reaction and multiply it by 2 to balance the electrons: 
2Pb + 2Zn^2+ --> 2Pb^2+ + 2Zn

Now we can add the reduction and oxidation half-reactions:
Zn^2+ + 2e^- + 2Pb --> 2Pb^2+ + 2Zn
cancel out the electrons
2Pb + Zn^2+ --> 2Pb^2+ + Zn
So,
E°cell = E°reduction - E°oxidation
E°cell = (-0.76 V) - (-0.13 V)
E°cell = -0.63 V

But the question asks for the positive value of E°cell, so we flip the overall reaction: 
2Zn + 2Pb^2+ --> 2Pb + Zn^2+

And flip the sign of E°cell: 
E°cell = -E°cell
E°cell = 0.63 V

Therefore, the answer is D (+1.130 V) since the negative value of E°cell is 0.63, then its positive value is 1.130.

Consider the Following Half-Reactions