Question

Equal volumes of two solutions of a strong acid having `pH 3` and `pH 4` are mixed together. The `pH` of the resulting solution will then be equal to
A. `3.5`
B. `3.26`
C. `7`
D. `1.0`

Answer 1

Correct Answer - B
`pH=3 implies [H_(3)O^(+)]_(1)=10^(-3)`
`pH=4 implies [H_(3)O^(+)]_(2)=10^(-4)`
As equal volumes are mixed so after mixing
`[H_(3)O^(+)]_(1)=(10^(-3))/(2)`
`[H_(3)O^(+)]_(2)=(10^(-4))/(2)`
`[H^(+)]_(mixture)=[0.5xx10^(-3)+0.5+10^(-4)]lt`
`pH=3.26`