Chemistry - Thermochemistry Question with Solution | TestHub
ChemistryThermochemistryEnthalpy of ReactionMedium2 minQB
ChemistryMediumsingle choice
Passage / Comprehension
For the reaction at 25°C, X2O4(l) → 2XO2(g), Δ E° = 2.1 kcal and ΔS° = 20 cal/K.
ΔG° for the reaction is
Options:
Answer:
A
Solution:
The change in the number of moles of gas, Δ ng, is calculated as:
Δ ng = 2 - 0 = 2
The change in enthalpy, Δ H, can be determined using the relationship:
Δ H = Δ E + Δ ng RT
Given Δ E = 2100 cal, R = 2 cal/K·mol, and T = 298 K:
Δ H = 2100 + 2(2)(298) = 2100 + 1192 = 3292 cal
The change in Gibbs free energy, Δ G, is calculated using the formula:
Δ G = Δ H - TΔ S
Given Δ S = 20 cal/K:
Δ G = 3292 - 298(20) = 3292 - 5960 = -2668 cal
This value is approximately -2.7 kcal. This corresponds to option (a).
Stream:JEESubject:ChemistryTopic:ThermochemistrySubtopic:Enthalpy of Reaction
⏱ 2mℹ️ Source: QB
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