GATE 2021 MT – Question 27
Copper melts at 1358 K with melting enthalpy 13400 J/mol. Its liquid-to-solid free-energy change at 1058 K is ______ J/mol (nearest integer). Assume $C_p^{liquid}=C_p^{solid}$.
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Correct answer: -2962 to -2958
Explanation
Equal heat capacities make fusion enthalpy and entropy differences temperature-independent. For liquid→solid, ΔG=−ΔHm(1−T/Tm)=−13400(1−1058/1358)=−2960.24 J/mol. Rounded, **−2960 J/mol**.