Lecture_16A - 8. Vapor pressure and Changes of state...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
8. Vapor pressure and Changes of state • Kinetic energy of the liquid molecules at the surface are not all the same ( distribution ). • When the kinetic energy of a given molecule overcomes the potential energy of attraction between the neighboring liquid molecules, this molecule escapes from the liquid and goes into the vapor. • Molecules tend to escape from the surface of a liquid and form a gas. Evaporation or Vaporization (endothermic process) . Heat of vaporization (or enthalpy of vaporization) energy required to vaporize 1.00 mole of liquid at a pressure of 1.00 atm. ( H vap ) For water: H vap. (H 2 O) = 40.7 kJ/mol Experiment: Evaporation of a liquid in a closed container. • Molecules evaporate, then as more molecules go into the vapor, the rate of collisions with the surface of the liquid increases (more molecules return to the liquid). the rate of condensation gradually increases. • When the two rates become
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

Lecture_16A - 8. Vapor pressure and Changes of state...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online