A 810-g quantity of ethanol, in the liquid state at its melting point of -114°C, is frozen at atmospheric pressure. The heat of fusion of ethanol is 1.04 × 10⁵ J/kg, the molecular mass is 46.1 g/mol, and the ideal gas constant is R = 8.314 J/(mol∙K). The change in the entropy of the ethanol as it freezes is closest to

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Quizplus · Accepted Answer

The change in entropy (ΔS) during freezing is given by ΔS = -Q/T, where Q is the heat removed and T is the temperature in Kelvin. Q = mass × heat of fusion = 0.810 kg × 1.04 × 10^5 J/kg = 84240 J. T = -114°C = 159 K. ΔS = -84240 J / 159 K ≈ -530 J/K, closest to -540 J/K.

A 810-G Quantity of Ethanol, in the Liquid State at Its