Calculate the pH of solution when 100mL, 0.1MC H _ 3 COOH and 100mL, 0.1MHCOOH are mixed together. (Given: K _ a (C H _ 3 COOH) = 2 × 10 ^ – 5 , K _ a (HCOOH) = 6 × 1 0 ^ – 5 )

Question

Quantrex Academy · Accepted Answer

Correct answer: 2.7

As the volume is doubled, concentration would be half. The total

\left[{\text{H}}^{\text{+}}\right]

is obtained by addition of

\left[{\text{H}}^{\text{+}}\right]

from both acids.

[ {H}^{+} ] = \sqrt{\left({K}_{a1}{C}_{1} + {K}_{a2}{C}_{2}\right)}

= \sqrt{\left(2 \times 1{0}^{- 5} \times \dfrac{0.1}{2} + 6 \times 1{0}^{- 5} \times \dfrac{0.1}{2}\right)}

= 2 \times 1{0}^{- 3}

pH = 2.7

Calculate the pH of solution when 100mL, 0.1MC H _ 3 COOH and...

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