Consider a galvanic cell based upon the following half reactions: Ni 2+ + 2e - N

Question

Consider a galvanic cell based upon the following half reactions:

Ni2+ + 2e- Ni      -0.27 V
Cr3+ + 3e- Cr      -0.73 V

How many of the following responses are true?

1. Adding equal amounts of water to both half reaction vessels will increase the potential of the cell
2. Decreasing the mass of the Cr will change the initial potential of the cell
3. Cr is being oxidized during the reaction
4. Increasing the concentration of Ni2+ (assuming no volume change) will increase the potential of the cell
5. Increasing the concentration of Cr3+ (assuming no volume change) will increase the potential of the cell

Explanation / Answer

overall cell reaction is:

2 Cr (s) + 3 Ni2+ (aq.) -----------> 2 Cr3+ (aq.) + 3 Ni (s)

Nernst equation,

Ecell = E0cell - (0.05916/6) Log[Cr3+]2/[Ni2+]3

* Cr being oxidised during the reaction. (its reduction potential is low)

* Increasing the concentration of Cr3+ will increase the potential of the cell.

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