JEE Main 2025 Jan 22 Shift 1, Chemistry Q21: Law of Chemical Equilibrium And Equilibrium Constant

JEE Main2025Jan 22, Shift 1Chemistry

Some CO $_{2}$ gas was kept in a sealed container at a pressure of 1 atm and at 273 K. This entire amount of CO $_{2}$ gas was later passed through an aqueous solution of Ca(OH) $_{2}$ . The excess unreacted Ca(OH) $_{2}$ was later neutralized with 0.1 M of 40 mL HCl. If the volume of the sealed container of CO $_{2}$ was x, then x is _____ cm $^{3}$ (nearest integer).

[Given : The entire amount of CO $_{2}$ (g) reacted with exactly half the initial amount of Ca(OH) $_{2}$ present in the aqueous solution.]

Your answer

Solution

Let moles of CO $_{2}$ $= n$ . Then moles of Ca(OH) $_{2}$ initially in solution $= 2 n$ (since CO $_{2}$ reacted with exactly half).

Unreacted Ca(OH) $_{2} = n$ mol. Neutralising with HCl:

$2 \times n = M_{HCl} \times V_{HCl} = 0.1 \times \frac{40}{1000} = 4 \times 1 0^{- 3}$ equivalents.

$\Rightarrow n = 2 \times 1 0^{- 3}$ mol.

Volume of CO $_{2}$ at STP $= n \times 22400 = 2 \times 1 0^{- 3} \times 22400 = 44.8$ cm $^{3} \approx 45$ cm $^{3}$ .

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JEE Main 2025 Jan 22 Shift 1, Chemistry Q21: Law of Chemical Equilibrium And Equilibrium Constant

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