Chemistry · Thermochemistry and states of matter

Heating Curve and Phase Change Explorer

A sample of ice starts below its melting point. Add heat with the slider and watch the temperature, the particles, and the point on the heating curve.

Temperature rises while heat goes into faster particle motion. On the flat parts of the curve, heat goes into breaking attractions between particles, so the temperature stays constant while the phase changes.

Model notes

Constants used for water: specific heat of ice 2.09 J/(g·°C), heat of fusion 334 J/g, specific heat of liquid water 4.184 J/(g·°C), heat of vaporization 2260 J/g (at 100 °C and 1 atm), specific heat of steam 2.01 J/(g·°C).
The calculation is ideal: no heat is lost to the surroundings, pressure is 1 atm, and the sample is heated slowly enough that it is at one temperature throughout.
The particle picture is a model. Only the relative motion and spacing are meant to be read: fixed positions with small vibration (solid), close and moving past each other (liquid), far apart and fast (gas).
Boiling 1 g of water takes 2260 J, about 5.4 times the 418 J needed to warm 1 g of liquid water from 0 °C to 100 °C. Compare the bars to see the scale.

Sources

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