Answer to Question #319040 in Physical Chemistry for Sir mencho

Question

In an electrolysis of cuso4 between copper electrodes ,the total mass of copper deposited at the cathode was 0.153g and the mass of copper per unit volume of the anode liquid before and after analysis were 0.79g and 0.91g respectively . Calculate the transport number of cu2+ and so42+

Answer 1

$\Delta$ W(Cu²⁺)_k = 0.153 g;

W(Cu²⁺)_{a, before} = 0.79 g;

W(Cu²⁺)_{a, after} = 0.91 g;

$\Delta$ W(Cu²⁺)_a = W(Cu²⁺)_{a, after} - W(Cu²⁺)_{a, before} = 0.91 - 0.79 = 0.12 g;

Fall in concentration due to migration of Cu²⁺ : $\Delta$(Cu²⁺) = $\Delta$ W(Cu²⁺)_k - $\Delta$ W(Cu²⁺)_a = 0.153 - 0.12 = 0.033 g;

Transport number of Cu²⁺ : t(Cu²⁺) = $\Delta$(Cu²⁺) / $\Delta$ W(Cu²⁺)_k = 0.033/0.153 = 0.216;

Transport number of SO₄^2- : t(SO₄^2-) = 1 - t(Cu²⁺) = 1 - 0.216 = 0.784.

Answer: t(Cu²⁺) = 0.216;

t(SO₄^2-) = 0.784.