Chapter 6 - Phase Diagrams

Phase

A state of matter that is uniform throughout, not only in chemical composition but also in physical state

Constituent of a system

A chemical species (an ion or a molecule) that is present

Variance of a system

The number of intensive variables that can be changed independently without disturbing the number of phases in equilibrium

Bivariant system

When in a single-component, single-phase system, the pressure and temperature may be changed independently without changing the number of phases

Phase rule

A general relation between the variance, the number of components, and the number of phases at equilibrium, for a system of any composition

Thermal analysis

It takes advantage of the effect of the enthalpy change during a first-order transition

Differential scanning calorimetry

Useful for solid-solid transitions, where simple visual inspection of the sample may be inadequate

Partial vapor pressure

Total vapor pressure

Temperature-composition diagram

A phase diagram in which the boundaries show the composition of the phases that are in equilibrium at various temperatures

Upper critical solution temperature

The highest temperature at which phase separation occurs

Lower critical solution temperature

Temperature in which the system mix in all proportions and above which they form two phases

Eutectics

The mixture with the lowest melting point