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 ofthe following statements is/are correct ?

• A. Increase in the mass of cathode = $3.174g$
• B. Decrease in the mass of anode = $3.174g$
• C. No change in the mass of electrodes
• D. The ratio between the change in the mass of cathode to anode is $1:2$

Answer 1

Answer: (A), (B)

The correct options are
A Increase in the mass of cathode = $3.174g$
B Decrease in the mass of anode = $3.174g$

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

Hence, options $A$ and $B$ are correct.