Question

A current of 2.68 A is passed for 1.0 hour through an aqueous solution of $CuS{O}_4$ using copper electrodes. Which of the following statements is/are correct ?

• A. Decrease in the mass of anode = 3.174 g
• B. No change in the mass of electrodes
• C. The ratio between the change in the mass of cathode to anode is 1 : 2
• D. None of these

Answer 1

Answer: (A)

Decrease in the mass of anode = 3.174 g

As given,

Number of Faradays = $\frac{1t}{96500}=\frac{2.68\times 1\times 3600}{96500}=0.1$

At cathode : $C{u}^{2+}\left(aq\right)+2e^{-}\to Cu\left(s\right)$

$\Rightarrow 2F\equiv 1molCu$

$\Rightarrow 0.1F\equiv 0.05moleCu\equiv 0.05\times 63.5gCu$

$=3.175gCudeposited$

At anode : $Cu\left(s\right)\to C{u}^{2+}\left(aq\right)+2e^{-}$

$\Rightarrow$ 2 F $\equiv$ 1 mole Cu $\Rightarrow$ 0.1 F $\equiv$0.05 mole Cu $\equiv 0.065,\times 63.5gCu$

$=3.175gCu$ used