Intermolecular Forces in Phase Changes

[bravoghost]

Would the energy of a phase change (let's say going from a gas to a liquid) be equal to the energy of all newly formed intermolecular bonds being formed as the gas transitions to liquid?

[DJBruce]

Would the energy of a phase change (let's say going from a gas to a liquid) be equal to the energy of all newly formed intermolecular bonds being formed as the gas transitions to liquid?

 

The energy needed to vaporize a substance is the same amount of energy given off when that energy condenses. Condensation is actually and exothermic process as the motion of particles decrease thus decreasing their kinetic energy.

[mississippichem]

Intermolecular forces are usually negligible in the gas phase, but at high temeratures, pressures and mico-volumes, the behaviour of gases deviates significantly from the ideal gas equation.

To answer your question: No, not exactly, but the enthalpy of vapoization (given by the Clausius-Clapeyron equation) accounts for the overcoming of van-der Waals, and or hydrogen-bonding interactions depending on the specific liquid. Look up Born-Haber Cycles in chemical thermodynamics