200 mL of 0.01 M HCl is mixed with 400 mL of $0.01 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$. The pH of the mixture is \_\_\_\_ .

JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Equilibrium

200 mL of 0.01 M HCl is mixed with 400 mL of

0.01 M H_{2} SO_{4}

. The pH of the mixture is ____ .

Answer: (B)

HCl contributes: 0.01 M × 200 mL = 2 mmol

H^{+}

H_{2} SO_{4}

contributes: 0.01 M × 2 × 400 mL = 8 mmol

H^{+}

(since

H_{2} SO_{4}

is diprotic).

Total

H^{+}

= 2 + 8 = 10 mmol.
Total volume = 200 + 400 = 600 mL.

[H^{+}]

= 10/600 = 1/60 M.

pH = -log(1/60) = log(60) ≈ 1.78.

Answer: (B) 1.78

JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Single correct option