Question

When a solution of $CuS{O}_4$ is electrolysed for $15$ minutes with a current of $1$ amp, then the mass of $Cu$ deposited at the cathode will be

• A. 30 gm
• B. 0.3 gm
• C. 0.03 gm
• D. 3 gm

Answer 1

Answer: (B)

$I=1.0A,t=15min=15\times 60=900s$
Quantity of electricity passed = $I\times t$
$=1.0\times 900$ coulombs
$=900C$
The reaction occurring at the cathode is
$C{u}^{2+}+2e^{-}\to Cu$
Thus, $2F$ i.e. $2\times 96500C$ deposit $Cu$
$1mole=63.5g$
and $900C$ will deposit $Cu=\frac{63.5}{2\times 96500}\times 900$
$=0.26g$
$\approx 0.3g$