Q62 / 160 · JIPMER 2006 · Chemistry

Given pH of a solution $A$ is 3 and it is mixed with another solution $B$ having pH 2 . If both mixed, then resultant pH of the solution will be :

  • A
    3.2
  • Correct answer
    B
    1.9
  • C
    3.4
  • D
    3.5

Solution

$\begin{aligned} & \mathrm{pH} \text { of } A=3 \quad \mathrm{pH} \text { of } B=2 \\ & \therefore\left[\mathrm{H}^{+}\right]=10^{-3} \mathrm{M}, \quad\left[\mathrm{H}^{+}\right]=10^{-2} \mathrm{M} \\ & \text { Total }\left[\mathrm{H}^{+}\right] \\ & =10^{-3}+10^{-2}=10^{-3}+10 \times 10^{-3} \\ & =11 \times 10^{-3} \\ & \therefore \quad \mathrm{pH}=-\log _{10}\left[\mathrm{H}^{+}\right]=-\log \left(11 \times 10^{-3}\right) \\ & =3-\log 11 \\ & =3-1.04=1.96 \\ & \end{aligned}$

Hence, the correct answer is option: 'B'.

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