The entropy versus temperature plot for phases a and b at 1 bar pressure is given. S T and S 0 are entropies of the phases at temperatures T and 0 K , respectively. The transition temperature for

Question

The entropy versus temperature plot for phases a and b at 1 bar pressure is given.

$S_{T}$ and $S_{0}$ are entropies of the phases at temperatures T and 0 K , respectively.

The transition temperature for α to β phase change is 600 K and C_P,β – C_P,α = 3 J mol^-1K^-1 .

Assume (C_P,β – C_P,α ) is independent of temperature in the range of 200 to 700 K. C_P,α and C_P,β are heat capacities of α and β phases, respectively.

Select the correct statement(s).

TestHub · Accepted Answer

α → β (C) at 600 K Δ r ​ S = S β ​ − S α ​ = 8 − 4 = J / mol − K at transition temperature Δ r ​ G = 0 Δ H 600 ​ = T Δ S = 600 × 4 = 2400 J / mol − K . (A) Δ H 300 ​ = Δ H 600 ​ + Δ r ​ C P ​ Δ T ​ = 2400 + 3 × ( 300 − 600 ) ​ = 1500 J / mol = 1.5 kJ / mol ​ (B) Δ H 500 ​ = Δ H 600 ​ + Δ r ​ C P ​ Δ T ​ = 2400 + 3 × ( 500 − 600 ) ​ = 2100 J / mol = 2.1 kJ / mol . ​ (D) Δ S 200 ​ = Δ S 600 ​ + Δ r ​ C P ​ ln T 1 ​ T 2 ​ ​ = 4 + 3 ln 600 200 ​ = 0.7 J / mol − K .

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