JEE PYQ: States Of Matter Question 1
Question 1 - 2021 (16 Mar Shift 2)
At $25^\circ\text{C}$, 50 g of iron reacts with HCl to form $\text{FeCl}_2$. The evolved hydrogen gas expands against a constant pressure of 1 bar. The work done by the gas during this expansion is ____ J. (Round off to the Nearest Integer)
[Given: $R = 8.314 \text{ J mol}^{-1} \text{K}^{-1}$. Assume, hydrogen is an ideal gas. Atomic mass of Fe is 55.85u]
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Answer: 2218
Solution
$\text{Fe} + 2\text{HCl} \to \text{FeCl}_2 + \text{H}_2(g)$. Moles of Fe = $\frac{50}{55.85}$. Work done $= \Delta n_g RT = \frac{50}{55.85} \times 8.314 \times 298 \approx 2218$ J.
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