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Electrochemistry

Question
CBSEENCH12006132

Calculate the equilibrium constant Kc for the reaction at 298 K.
                        3Sn4+ + 2 Cr   3Sn2++2Cr3+
(Given E°Sn4+/Sn2+ = 0.15 V;  E°Cr3+/Cr = -074 V). = 0.34 V;

Solution
E°cell = E°Sn4+/Sn2+ - E°Sn4+/Sn2+  - E°Cr3+/Cr = 0.15 - (-0.74) = 0.89 V
It is clear from the given equation that electrons involved in the reaction (n) = 6
                       log KC = E°cell × n0.059

or                      log KC = 0.89 × 6 0.059 = 90.508
or                            KC = antilog 90.508
or                            KC = 3.221 × 1090.