Question

Excess of carbon dioxide is passed through $50 \,mL$ of $0.5\, M$ calcium hydroxide solution. After the completion of the reaction, the solution was evaporated to dryness. The solid calcium carbonate was completely neutralised with $0.1\, N$ Hydrochloric acid. The volume of Hydrochloric acid required is (At. mass of calcium = $40$)

• A. $500\,cm^3$
• B. $400\,cm^3$
• C. $300\,cm^3$
• D. $200\,cm^3$

Answer 1

Answer: (A)

$500\,cm^3$

Answer 2

No. of millimoles of $Ca ( OH )_{2}=50 \times 0.5=25$

No. of millimoles of $CaCO _{3}=25$

No. of milliequivalents of $CaCO _{3}=50$
$\therefore$ Volume of $0.1 \,N HCl =\frac{50}{0.1}=500 \,cm ^{3}$