600 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 ______ $\times 10^{-2}$. (Nearest integer) [Given $\log 2=0.30, \quad \log 3=0.48$ $\log 5=0.69$ $\log 7=0.84$ $\log 11=1.04]$

JEE Main · 2023 · 30 Jan 2023 · Shift 1 · Equilibrium

600 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 ______

\times 1 0^{- 2}

. (Nearest integer)
[Given

lo g 2 = 0.30, lo g 3 = 0.48

lo g 5 = 0.69

lo g 7 = 0.84

lo g 11 = 1.04]

Answer: 186

The hydrogen ion from the hydrochloric acid is

600 \times 0.01 = 6

mmol. Sulphuric acid is diprotic, so it supplies

400 \times 0.01 \times 2 = 8

mmol of

H^{+}

. The total of

14

mmol in the combined

1000

mL gives

[H^{+}] = 14 \times 1 0^{- 3} M

. Then

pH = - lo g (14 \times 1 0^{- 3}) = 3 - lo g 14 = 3 - (lo g 2 + lo g 7) = 3 - (0.30 + 0.84) = 1.86

. In the form asked, the pH is

186 \times 1 0^{- 2}

JEE Main · 2023 · 30 Jan 2023 · Shift 1 · Integer answer