KVPY Sample Paper KVPY Stream-SX Model Paper-27

Electrolysis of a solution of \[HSO_{4}^{\,-}\] ions produces \[{{S}_{2}}{{O}_{8}}^{-\,-}.\] Assuming 75% current efficiency, what current should be employed to achieve a production rate of 1 mole of \[{{S}_{2}}{{O}_{8}}^{-\,-}\] per hour?

A) + 71.5 amp

B) 35.7 amp

C) 142.96 amp

D) 285.93 amp

Correct Answer: A

Solution :

\[2HSO_{4}^{-}\xrightarrow{{}}{{S}_{2}}O_{8}^{-\,-}+2{{H}^{+}}+2{{e}^{-}}\] so required rate \[=1\,\text{mole/hr}\]

\[=2\,\text{mole}\] of \[{{e}^{-}}\text{/hr}\]

\[=\frac{2\times 96500}{3600\sec }=\frac{2\times 965}{36}\]

\[A\simeq 53.6\,A\]

so required current \[=\frac{4}{3}\times 536.6A=71.4A\]