60 mL of 0.15 M HCl and 80 mL of 0.05 M H2SO4 are mixed with 25 mL of 0.20 M Ba(OH)2. Treating H2SO4 as fully ionised (ignore any precipitate effects on pH) and volumes as additive, find the pH to two decimals.

JEE Advanced levelNumerical answerDifficulty 3 of 3ie042

$60 mL$ of $0.15 M$ $HCl$ and $80 mL$ of $0.05 M$ $H X_{2} SO X_{4}$ are mixed with $25 mL$ of $0.20 M$ $Ba (OH) X_{2}$ . Treating $H X_{2} SO X_{4}$ as fully ionised (ignore any precipitate effects on pH) and volumes as additive, find the pH to two decimals.

Numerical answer type, tolerance 0.01.

n (H X^{+}) = 9 + 8 = 17 mmol

;

n (OH X^{-}) = 2 \times 5 = 10 mmol

. Excess

H X^{+} = 7 mmol

165 mL

gives

[H X^{+}] = 0.0424 M

and

pH = 1.372 \approx 1.37