Chemical And Ionic Equilibrium Result Question 12
12. How many litres of water must be added to $1 \mathrm{~L}$ of an aqueous solution of $\mathrm{HCl}$ with a $\mathrm{pH}$ of $1$ to create an aqueous solution with $\mathrm{pH}$ of $2$ ?
(2013 Main)
(a) $0.1 \mathrm{~L}$
(b) $0.9 \mathrm{~L}$
(c) $2.0 \mathrm{~L}$
(d) $9.0 \mathrm{~L}$
Show Answer
Answer:
Correct Answer: 12. ( d )
Solution:
$\begin{aligned} \mathrm{pH}=1 \therefore\left[\mathrm{H}^{+}\right] & =10^{-1}=0.1 \mathrm{M} \\ \mathrm{pH} & =2 \therefore\left[\mathrm{H}^{+}\right]=10^{-2}=0.01 \mathrm{M} \end{aligned}$
For dilution of $\mathrm{HCl}, M_1 V_1=M_2 V_2$
$\begin{aligned} 0.1 \times 1 & =0.01 \times V_2 \\ V_2 & =10 \mathrm{~L} \end{aligned}$
Volume of water to be added $=10-1=9 \mathrm{~L}$
BETA
