States of matter

Temperature

20 °C

cold hot

Freezing inactive

Pressure

1.0 bar

low high

Phase diagram

Water: 20 °C / 1.0 bar

Display

Macroscopic level Simplified particle level Molecular representation Show partial charges Show hydrogen bonds

Oxygen δ− Hydrogen δ+ Hydrogen bond

Sources

Phase diagram
Wikipedia/Wikimedia Commons: File: Phasendiagramme.svg, adapted excerpt.

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Information

Temperature, pressure and state of matter

Water can exist as a solid, liquid or gas. Which state is stable depends on temperature and pressure. In the phase diagram, every point represents a particular combination of these two variables.

At the macroscopic level, water appears as a continuous substance. The simplified particle model shows how particle spacing, order and motion change. The molecular representation additionally reveals the bent shape of water molecules, their partial charges and hydrogen bonds.

Tasks

Represent the same point in the phase diagram at all three levels in turn. Compare which features are visible at each level.
Keep the pressure constant and increase the temperature step by step. Describe the changes during melting and vaporisation.
Select a temperature near the boiling point and change the pressure. Explain the movement of the marker and the observed phase transition.
Activate partial charges and hydrogen bonds in the molecular representation. Compare their significance in ice, liquid water and water vapour.