Question

Assuming no change in volume, the time required to obtain solution of $pH=12$ by electrolysis of $50ml.0.1MNaCl$ (using current of 0.5 amp) will be

• A. 65 sec
• B. 96.5 sec
• C. 965 sec
• D. 9.65 sec

Answer 1

The correct option is B 96.5 sec

$\left[H^{+}\right]={10}^{-12}M$
$\therefore \left[O{H}^{-}\right]={10}^{-2}M$
Number of moles of $NaOH$ is $50mL$ solution $=\frac{MV}{1000}=\frac{{10}^{-2}\times 50}{1000}$
$=5\times {10}^{-4}$
Mass of $NaOH$ in the solution $=5\times {10}^{-4}\times 40=2\times {10}^{-2}g$
$W=\frac{ItE}{96500}$
$2\times {10}^{-2}=\frac{0.5\times t\times 40}{96500}$
$t=96.5sec$