Consider the following reaction: 2A(g) + B(g) -> 2D(g) U^° = -10 kJ,mol-1 and S^° = -44 J,K-1 at 298 K. Identify the correct option with G^° for the reaction and the spontaneity of the reaction at 298 K. (Given: R = 8.31 J,mol-1K-1)

Correct answer: (C) +0.63568 kJ,mol-1, non-spontaneous. Answer: (C) +0.63568 kJ,mol-1, non-spontaneous Solution: Change in moles of gas: n_g = 2 - (2+1) = -1. First convert U^° to H^°: H^° = U^° + n_g RT = -10 + (-1)(8.31)(298)/1000 = -10 - 2.476 = -12.476 kJ,mol-1. Then G^° = H^° - T S^° = -12.476 - 298 × (-44)/1000 = -12.476 + 13.112 = +0.636 kJ,mol-1. Since G^° > 0, the reaction is non-spontaneous at 298 K.

NEET 2026 (Phase 1) · ChemistryPrevious Year Question

Consider the following reaction: $2 A (g) + B (g) 2 D (g)$ $Δ U^{\circ} = - 10 k J m o l^{- 1}$ and $Δ S^{\circ} = - 44 J K^{- 1}$ at $298 K$ . Identify the correct option with $Δ G^{\circ}$ for the reaction and the spontaneity of the reaction at $298 K$ . (Given: $R = 8.31 J m o l^{- 1} K^{- 1}$ )

Answer: (C) $+ 0.63568 k J m o l^{- 1}$ , non-spontaneous. \textbf{Answer:} (C) $+ 0.63568 k J m o l^{- 1}$ , non-spontaneous \textbf{Solution:} Change in moles of gas: $Δ n_{g} = 2 - (2 + 1) = - 1$ .

A. $- 1.635 k J m o l^{- 1}$ , spontaneous
B. $- 0.63568 k J m o l^{- 1}$ , spontaneous
C. $+ 0.63568 k J m o l^{- 1}$ , non-spontaneous✓
D. $+ 1.635 k J m o l^{- 1}$ , non-spontaneous

Correct Answer

Solution & Explanation

\textbf{Answer:} (C) $+ 0.63568 k J m o l^{- 1}$ , non-spontaneous \textbf{Solution:} Change in moles of gas: $Δ n_{g} = 2 - (2 + 1) = - 1$ . First convert $Δ U^{\circ}$ to $Δ H^{\circ}$ : $Δ H^{\circ} = Δ U^{\circ} + Δ n_{g} R T = - 10 + (- 1) (8.31) (298) /1000 = - 10 - 2.476 = - 12.476 k J m o l^{- 1}$ . Then $Δ G^{\circ} = Δ H^{\circ} - T Δ S^{\circ} = - 12.476 - 298 \times (- 44) /1000 = - 12.476 + 13.112 = + 0.636 k J m o l^{- 1}$ . Since $Δ G^{\circ} > 0$ , the reaction is non-spontaneous at $298 K$ .

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Consider the following reaction: 2A(g)+B(g)​2D(g) ΔU∘=−10 kJmol−1 and ΔS∘=−44 JK−1 at 298 K. Identify the correct option with ΔG∘ for the reaction and the spontaneity of the reaction at 298 K. (Given: R=8.31 Jmol−1K−1)

Solution & Explanation

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