Question

Calculate the theoretical potential of the following cell. Is this cell as written galvanic or electrolytic? Pt | Cr3+ (3.00x10-2 M), Cr2+ (4.00x10-5 M) || Sn2+ (2.00x10-2 M), Sn4+ (2.00x10-4 M)| Pt

Answer 1

Sn⁴⁺ + 2e^- Sn²⁺           E^o = +0.15 V

2Cr²⁺ 2Cr³⁺ + 2e^-        E^o = +0.84 V

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Sn⁴⁺ + 2Cr²⁺ Sn²⁺ + 2Cr³⁺ E^o = 0.15 + 0.84 = 0.99 V

Q = [Cr³⁺]²[Sn²⁺]/[Sn⁴⁺][Cr²⁺]²

Q = (3.00 x 10^-2)² (2.00 x 10^-2) / (2.00 x 10^-4)(4.00 x 10^-5)² = 5.625 10⁷

E = E⁰ - (0.0591/n) log Q

E = 0.99 - (0.0591/2) log (5.625 10⁷)

E = 0.761 V