Phase Diagrams
Phase diagrams show what phase (solid, liquid or gas) a substance will be in at a given temperature and pressure.
The line between the solid/liquid regions (in the diagram below, green) gives the melting point of the substance at each pressure.
The line between the liquid/gas regions (in the digram below, blue) gives the boiling point of the substance at each pressure.
The phase diagram for water is slightly different from most: the solid/liquid phase boundary tilts to the LEFT, not the right. This corresponds to the fact that water takes up more space as a solid (ice) than as a liquid.
- Temperature/Pressure combinations that lie on the left of all the lines: Substance will be SOLID
- Temperature/Pressure combinations that lie below all the lines: Substance will be GAS
- Temperature/Pressure combinations that lie between two lines: Substance will be LIQUID
- Temperature/Pressure combinations that lie above and to the right of the critical point: Substance will be a SUPERCRITICAL FLUID (not quite liquid, not quite gas)
The line between the solid/liquid regions (in the diagram below, green) gives the melting point of the substance at each pressure.
The line between the liquid/gas regions (in the digram below, blue) gives the boiling point of the substance at each pressure.
The phase diagram for water is slightly different from most: the solid/liquid phase boundary tilts to the LEFT, not the right. This corresponds to the fact that water takes up more space as a solid (ice) than as a liquid.
Phase Diagram of Most Substances
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Phase Diagram of Water
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Images modified from http://en.wikipedia.org/wiki/File:Phase-diag2.svg
