PHYSICS · Single correct · ISC · Physics · Behaviour of Perfect Gases and Kinetic Theory of Gases · Heat and Thermodynamics
Problem
Which of the following best explains why, for most substances at 1 atm, the molar energy required for the liquid → gas transition is significantly greater than that required for the solid → liquid transition?
(a) Because boiling occurs at a much higher temperature than melting, more energy is required to raise the sample to that higher temperature.
(b) Vibrational motion increases much more during vaporization than during melting, so additional energy is needed.
(c) Intermolecular forces must be almost completely overcome to separate molecules into the gas phase, whereas they are only partially disrupted to form a liquid.
(d) Molecules must overcome additional repulsive forces when entering the gas phase, whereas melting involves only attractive forces, so vaporization requires more energy.