Question

Equal volume of solutions of $pH$ values $1,3,5$ and $6$ are mixed. The $pH$ of resultant solution is nearly:

• A. $1.3$
• B. $2.7$
• C. $1.6$
• D. $3.6$

Answer 1

Answer: (C)

$1.6$

The $pH$ of solution is the negative logarithm of hydrogen ion concentration.

$pH=-log\left[H^{+}\right]$.

Hence, $\left[H^{+}\right]={10}^{-pH}$

pH of values $1,3,5$ and $6$ corresponds to hydrogen ion concentrations of $0.1M$, $0.001M$, $0.00001M$ and $0.000001M$ respectively.

Assume that $1$ L of each solution is mixed.

The concentration of the resulting solution is $\frac{0.1M+0.001M+0.00001M+0.000001M}{4}=0.025253M$.

$pH=-log\left[H^{+}\right]=-log\left(0.025253\right)=1.6$.

Hence, the $pH$ of the resultant solution is $1.6$.