Question

Equal volumes of three acid solutions of $pH3,4$ and $5$ are mixed in a vessel. What will be the $H^{+}$ ion concentration in the mixture?

• A. $3.7\times {10}^{-3}M$
• B. $1.11\times {10}^{-3}M$
• C. $1.11\times {10}^{-4}M$
• D. $3.7\times {10}^{-4}M$

Answer 1

The correct option is D $3.7\times {10}^{-4}M$

$M=\frac{M_1{V}_1+M_2{V}_2+M_3{V}_3}{V}$

Let volume be 1 liter for each acid.

$M_1,M_2,M_3$ are the $\left[H^{+}\right]$ ion conc of acid 1, 2, 3 respectively.

pH is the negative logarithm to the base 10 of the hydronium ion $H_3{O}^{+}$ concentration measured in mol/L.

Total $\left[H_3{O}^{+}\right]=\frac{{10}^{-3}+{10}^{-4}+{10}^{-5}}{3}M=0.00037M=3.7\times {10}^{-4}M$