Change of State
Latent heat
During a change of state, temperature stays constant while energy breaks or forms intermolecular bonds.
The flat sections on the graph show where latent heat is absorbed.
Heating Curve
Substance
Current Readings
Temperature
— °C
Time
0 s
Current State
—
Change of State is a free interactive simulation for GCSE Physics (Edexcel IGCSE 4PH1) in which students heat a substance and observe its heating and cooling curve, tracking temperature over time through melting and boiling. No login required — includes a worksheet and self-marking quiz.
Aim: To investigate the heating and cooling curves of a substance as it changes state.
- Select Water (ice → water → steam) from the dropdown and click Start Heating.
- Watch the particle model and the heating curve build up together — pause to note what's happening at each stage.
- Identify the two flat sections on the heating curve, where latent heat is being absorbed. Record the melting point and boiling point shown by each one.
- Click Reset, then repeat for Wax and Ethanol, recording the melting/boiling points for each.
- Compare your three substances — which has the highest melting point? Which changes state fastest?
- Think: why does the temperature stay constant during a change of state, even though the substance is still being heated?
Reading recorded!