MarksRiser
MarksRiser
AIIMS2019Chemistry-Thermodynamics

AIIMS 2019 Chemistry Gibbs Free Energy MCQ Question

Type: MCQ-numerical-Medium-Class 11

In conversion of lime-stone to lime,

CaCO3(s)→CaO(s)+CO2(g)\text{CaCO}_3(\text{s}) \rightarrow \text{CaO}(\text{s}) + \text{CO}_2(\text{g})

he values of ΔH∘\Delta\text{H}^\circ and ΔS∘\Delta\text{S}^\circ are +179.1 kJ mol−1+179.1\text{ kJ mol}^{-1} and 160.2 J/K160.2\text{ J/K} respectively at 298 K298\text{ K} and 1 bar1\text{ bar}. Assuming that ΔH∘\Delta\text{H}^\circ and ΔS∘\Delta\text{S}^\circ do not change with temperature, temperature above which conversion of lime-stone to lime will be spontaneous is

A

1118 K1118\text{ K}

B

1008 K1008\text{ K}

C

1200 K1200\text{ K}

D

845 K845\text{ K}

Correct Answer

Option A

Detailed Explanation

In the context of the Gibbs free energy equation, ΔG° = ΔH° - TΔS°, a spontaneous reaction occurs when ΔG° < 0. The derived condition T > ΔH°/ΔS° indicates that for the reaction to be spontaneous, the temperature must exceed 1118 K, which is a critical threshold. Since all provided options (A, B, C, D) are marked as N/A, it suggests that none of the options provide relevant information or alternative scenarios, reinforcing that option A is the only viable choice in this context. Understanding this relationship between enthalpy (ΔH°), entropy (ΔS°), and temperature (T) is essential for predicting reaction spontaneity.

Found an issue with this question?

Related Questions