Question

The resultant molarity of $H^{+}$ ions in a mixture of $100\text{mL}$ of $0.1\text{M}{H}_{2}S{O}_4$ and $200\text{mL}$ of $0.1\text{M}{H}_{3}P{O}_3$ is:

• A. 0.1 M
• B. 0.2 M
• C. 0.267 M
• D. 0.133 M

Answer 1

The correct option is B 0.2 M

The number of $H^{+}$ ions in $100\text{mL}$ of $0.1\text{M}{H}_{2}S{O}_4=2\times 100\times 0.1\text{mmol}$

The number of $H^{+}$ ions in $200\text{mL}$ of $0.1\text{M}{H}_{3}P{O}_3=2\times 200\times 0.1\text{mmol}$

Total volume of the solution $=100+200\text{mL}=300\text{mL}$

So, the resultant molarity of $H^{+}$ ions in the mixture$=\frac{2\times 100\times 0.1+2\times 200\times 0.1}{300}=0.2\text{M}$