Question

How many grams of sulphuric acid is to be dissolved to prepare $200mL$ aqueous solution having concentration of $[H_3{O}^{+}]$ ions $1M$ at $25^{\circ }C$ temperature?

• A. $4.9g$
• B. $19.6g$
• C. $9.8g$
• D. $0.98g$

Answer 1

Answer: (C)

Two $[H_3{O}^{+}]$ ions are obtained from $1M{H}_{2}S{O}_4$.
$\therefore$ One $[H_3{O}^{+}]$ ion is obtained from $0.5M{H}_{2}S{O}_4$.
Molarity $=\frac{m\left(H_{2}S{O}_4\right)\times 1000}{M\left(\text{molar mass}{H}_{2}S{O}_4\right)}\times \text{volume of solution}(mL)$
$0.5=\frac{m\times 1000}{98\times 200}$
$m=\frac{0.5\times 98\times 200}{1000}$
$=9.8g$