Q40 / 180 · KCET 2009 · Chemistry
Excess of carbon dioxide is passed through 50 $\mathrm{mL}$ of $0.5 \mathrm{M}$ calcium hydroxide solution. After the completion of the reaction, the solution was evaporated to dryness. The solid calcium carbonate was completely neutralised with $0.1 \mathrm{~N}$ hydrochloric acid. The volume of hydrochloric acid required is (Atomic mass of calcium $=40$ )
- A$300 \mathrm{~cm}^{3}$
- B$200 \mathrm{~cm}^{3}$
- Correct answerC$500 \mathrm{~cm}^{3}$
- D$400 \mathrm{~cm}^{3}$
Solution
No. of millimoles of $\mathrm{Ca}(\mathrm{OH})_{2}=50 \times 0.5=25$
No. of millimoles of $\mathrm{CaCO}_{3}=25$
No. of milliequivalents of $\mathrm{CaCO}_{3}=50$
$\therefore$ Volume of $0.1 \mathrm{~N} \mathrm{HCl}=\frac{50}{0.1}=500 \mathrm{~cm}^{3}$
Hence, the correct answer is option: 'C'.