Particle States & Heating

Chemistry · O Level · States of matter · Heating curves

Heat and cool water, follow its particles and discover why temperature stops rising during a change of state.

Free to explore. The interactive lab loads only when you start. No account or saved progress.

Things to try

Predict what happens to temperature while ice melts. Add energy and test your prediction.
Compare solid, liquid and gas particle motion. What changes and what stays the same?
Pause halfway through boiling. Explain where the added energy goes.
Cool steam back into water and then ice. Follow the same curve in reverse.

Solid particles vibrate near fixed positions. Liquid particles move past neighbours. Gas particles are widely separated and move freely.
At normal atmospheric pressure, pure water melts at 0°C and boils at 100°C.
During a phase change, energy changes intermolecular arrangements rather than raising temperature. Water molecules remain water molecules.
This ideal model neglects heat losses and uses approximate constant heat capacities. Particle spacing and motion are illustrative, not to scale.

A horizontal section of a heating curve does not mean heating has stopped. Identify the change of state and explain the energy transfer.

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