A chemist has 2.00 mol of ethanol at its normal boiling point (78.4 °C)

CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics

Problem

A chemist has 2.00 mol of ethanol at its normal boiling point (78.4 °C). The molar enthalpy of vaporization of ethanol is 38.6 kJ mol⁻¹. Which of the following gives the approximate quantity of heat that must be added and the corresponding orientation of the enthalpy arrow on an energy diagram? (a) 3.9×101 kJ3.9 \times 10^{1}\,\text{kJ} added; arrow points upward from liquid to vapor. (b) 7.7×101 kJ7.7 \times 10^{1}\,\text{kJ} released; arrow points downward from liquid to vapor. (c) 7.7×101 kJ7.7 \times 10^{1}\,\text{kJ} added; arrow points upward from liquid to vapor. (d) 7.7×101 kJ7.7 \times 10^{1}\,\text{kJ} added; arrow points downward from liquid to vapor.

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