L1.4: Phase Changes

• Each physical state of matter is a phase, a physically distinct, homogeneous part of a system. The properties of each phase are determined by the balance between the potential and kinetic energy of the particles.
• The potential energy, in the form of attractive forces, tends to draw particles together. The kinetic energy associated with movement tends to disperse particles.
• The boiling point of a liquid is the temperature at which the vapor pressure equals the external pressure.
• The normal boiling point of a substance is observed at standard atmospheric pressure or 760 torr
• As the external pressure on a liquid increases, the boiling point increases.