Given the table below predict the numerical value of the standard cell potential for the reaction: 2 Cr(s) + 3 Cu²⁺(aq) → 2 Cr³⁺(aq) + 3 Cu(s)
Half Reaction E° (volts)
(1) Cr³⁺ + 3 e- → Cr -0.74
(2) Cr³⁺ + e- → Cr²⁺ -0.41
(3) Cr₂O₇^2- + 14 H⁺ + 6 e- → 2 Cr³⁺ + 7 H₂O 1.33
(4) Cu⁺ + e- → Cu 0.52
(5) Cu²⁺ + 2 e- → Cu 0.34
(6) Cu²⁺ + e- → Cu⁺ 0.16

Question

Quizplus · Accepted Answer

To find the standard cell potential for the given reaction, we need to add the potentials for the half reactions that make up the reaction. We can simplify the given reactions to the following:

Cr → Cr3+ + 3e- E°= -0.74V      (multiply reaction (1) by 2)
Cu2+ + 2e- → Cu                E°= 0.34V  (add reaction (5) + (6))

We can cancel out the electrons to get the overall reaction:

2Cr + 3Cu2+ → 2Cr3+ + 3Cu

So the standard cell potential will be:

E°cell = E°(red, cathode) - E°(red, anode)
       = E°(Cu) - E°(Cr3+)
       = 0.34V - (-0.74V)
       = 1.08V

Therefore, the best choice is D.

Given the Table Below Predict the Numerical Value of the Standard