Question

Which of the following solutions will have pH close to 1.0?

• A. 100 ml of (M|10) HCl and 100 ml of (M|10) NaOH
• B. 55 ml of (M|10) HCl and 45 ml of (M|10) NaOH
• C. 10 ml of (M|10) HCl and 90 ml of (M|10) NaOH
• D. 75 ml of (M|5) HCl and 25 ml of (M|5) NaOH

Answer 1

The correct option is D 75 ml of (M|5) HCl and 25 ml of (M|5) NaOH

Miliequivalents of $H^{+}=75\times \frac{1}{5}=15$
Miliequivalents of ${}^{-}OH=25\times \frac{1}{5}=5$
Net Miliequivalents of $H^{+}=10$
Concentration of $H^{+}=\frac{10}{100}=0.1={10}^{-1}$
$pH=-log\left[H^{+}\right]$
= –log (0.1)
= 1