Heat it, cool it: watch matter change state
Add or remove heat from a sealed chamber of particles. Same particles, three very different arrangements.
Drag the slider right to add heat — or tap Add heat.
The heating curve: where does the heat go?
Latent heat in one idea
Temperature measures how fast the particles move. While a solid melts or a liquid boils, extra heat does not make them faster. It does work against the attractions that hold them together. So the thermometer sits still and the heat keeps flowing in. Boiling needs far more than melting because the particles must be separated completely, not just loosened.
An honest, simplified model
The curve uses water-like values for 1 g (ice 2.1, water 4.2, steam 2.0 J/g/K; melting 334 J; boiling 2256 J) with no heat lost and sea-level transition points. The 64 spheres are a cartoon: they show arrangement and motion, not real molecules, and the box size stays fixed. Heat is shared out as a model, so each particle frees at its own point in the plateau.