Question

$100$ml of a solution of HCl with pH value $3$ is diluted with $400$ml of water. The new pH of the solution is?

• A. $3.7$
• B. $5.3$
• C. $4.2$
• D. $5.6$

Answer 1

Answer: (A)

$3.7$

The concentration of $H^{+}$ for pH=3 is ${10}^{-3}M$

As $M_{1}V-1=M_2{V}_2$

$\left({10}^{-3}\right)\left(100\right)=M_2(100+400)$

$\Rightarrow M_2=2\times {10}^{-4}M$

The new value of $pH=-log(2\times {10}^{-4})$

$4-log2$

$=3.7$