Question

200 ml of 1 M $H_{2}S{O}_4$, 300 ml of 3 M $HCl$ and 100 ml of 2 M $HCl$ are mixed and made up to 1 litre. The proton concentration in the resulting solution is:

• A. 1.25 M
• B. 1.5 M
• C. 2.5 M
• D. 0.75 M

Answer 1

Answer: (B)

1.5 M

1 M $H_{2}S{O}_4$ solutio has 2M $H^{+}$ ions

Therefore, moles of $H^{+}$ in:

200 ml of 1M $H_{2}S{O}_4$ = $2\times 0.2L\times 1mol/L=0.4$

300 ml 0f 3M $HCl$ = $0.3L\times 3mol/L=0.9$

100 ml 0f 2M $HCl$ = $0.1L\times 2mol/L=0.2=1.5$

Total volume = 1L

So $\left[H^{+}\right]$ = 1.5 mol/L