Question

Equal volumes of two solutions with $pH=3$ and $pH=11$ are mixed. Then the $pH$ of the resulting solution is:

• A. $8$
• B. $7$
• C. $6$
• D. $0$

Answer 1

Answer: (B)

$7$

$pH$ of $1^{st}$ solution $=3$

$\left[H^{+}\right]={10}^{-3}$

$pH$ of $2^{nd}$ solution $=11$

$pOH$ is $(14-11)=03$

$\left[{OH}^{-}\right]={10}^{-3}$

now, they are mixed

$\left[H^{+}\right]={10}^{-3}$ and $\left[{OH}^{-}\right]={10}^{-3}$

equal concentrations mix together and neutralise each other.

Thus, $pH$ of resulting solution is $7$.