2: Phase Transitions and Liquids
- Page ID
- 284445
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- 2.1: Phase Transitions
- Phase changes can occur between any two phases of matter. All phase changes occur with a simultaneous change in energy. All phase changes are isothermal.
- 2.2: Heating Curves
- Freezing, condensation, and deposition, which are the reverse of fusion, sublimation, and vaporization—are exothermic. Thus heat pumps that use refrigerants are essentially air-conditioners running in reverse. Heat from the environment is used to vaporize the refrigerant, which is then condensed to a liquid in coils within a house to provide heat. The energy changes that occur during phase changes can be quantified by using a heating or cooling curve.
- 2.3: Intermolecular Forces
- All substances experience dispersion forces between their particles. Substances that are polar experience dipole-dipole interactions. Substances with covalent bonds between an H atom and N, O, or F atoms experience hydrogen bonding. The preferred phase of a substance depends on the strength of the intermolecular force and the energy of the particles.
- 2.4: Properties of Liquids - Vapor Pressure and Surface Tension
- All liquids evaporate. If volume is limited, evaporation eventually reaches a dynamic equilibrium, and a constant vapor pressure is maintained. All liquids experience surface tension, an imbalance of forces at the surface of the liquid. All liquids experience capillary action, demonstrating either capillary rise or capillary depression in the presence of other substances.