States of matter · melting, boiling, freezing

Phase Changes

Temperature20.0 °C

Ice0 cm³

Water100 cm³

Time0.0 s

Average molecular speed 587 m/s Water boils at 100.0 °C here Energy added 0 J

Set up the water and ice, choose how much heat to add, then press Play.

Starting conditions

These can only be changed before you press Play. Press Reset to change them again.

Water temperature20 °C Ice volume0 cm³ Altitude0 m

Add or remove heat0 J/s

View

Simulation speed

All liquid water

Melting point0.0 °C

Boiling point100.0 °C

Air pressure760 mmHg

Total mass100.0 g

Set the starting conditions. Choose a water temperature, how much ice to drop in, and what altitude you are at. There is always 100 cm³ of water to begin with.
Choose the heat. Slide Add or remove heat to the right to heat the beaker with the burner, or to the left to cool it. Leaving it at 0 J/s means no heat goes in or out.
Press Play. Watch the thermometer, the readouts along the top, and the graph on the right. Press Pause any time to read a value, and Reset to start over.
Switch to Micro view to see the individual water molecules instead of the bulk liquid. Watch how they slow down as it cools and speed up as it heats.
Watch for the flat parts of the graph. While ice is melting or water is boiling, the temperature stops changing even though heat is still going in. Those flat sections are the phase changes.
Turn up the altitude and look at the boiling point pill under the beaker. Higher up, the air pushes down less, so water boils at a lower temperature.

Tip: boiling all the water away takes a lot of energy. If you are waiting a long time, use the Simulation speed dropdown to run at 5× or 20×.