Question

The $pH$ of the solution produced when an aqueous solution of strong acid $pH$ $5$ is mixed with equal volume of an aqueous solution of strong acid of $pH=3$ is:

• A. $3.3$
• B. $3.5$
• C. $4.5$
• D. $4.0$

Answer 1

The correct option is A $3.3$

According to the question

$pH5=0.00001mole/l$

$pH3=0.001mole/l$

therefore,

$\left(H^{+}\right)$ $=$ $\frac{{10}^{-5}\times v+{10}^{-2}\times v}{2v}$

$\Rightarrow$ $=\frac{1.01\times {10}^{-3}}{2}$

$=5.05\times {10}^{-4}$

So,

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

$=-log(5.05\times {10}^{-4})$

hence the $pH$ is $=3.2967\Rightarrow 3.3$
Option A is correct.