Question

A current of $13.4A$ is passed through $1.0L$ of $1.0M$ $HCl$ solution by using $Pt$ electrodes for $1.0hr.$ The $pH$ of the solution after the experiment is over at $298K$ will be about.

• A. $0.20$
• B. $0.30$
• C. $0.40$
• D. $0.50$

Answer 1

The correct option is B $0.30$

$\left(B\right)0.30$

Change in coulombs $=13.4\times 1\times 60\times 60=48240$

Moles of electric charge $=\frac{48240}{96500}=0.5F$

Equivalent of HCl decomposed on electrolysis $=0.5$

Mili equivalents of HCl along electrolysis $=500$

Molarity of HCl after electrolysis $=\frac{500}{1000}=0.5M$

$\left[H^{+}\right]=5\times {10}^{-1}$

$pH=-\log \left[H^{+}\right]$

$pH=-\log 5\times {10}^{-1}=\mathrm{0.30.}$