Back to Chapter 11 · Between the Molecules
Where the energy goes during heating
Follow a pure water sample from ice to steam. Added heat changes temperature or phase, depending on the stage.
Schematic teaching diagram · labels and text explain each state.
Read the sequence
- Warm the ice from −20 °C to 0 °C. Within a phase, q = mcΔT; average kinetic energy increases with temperature.
- At the melting plateau, ice becomes liquid at 0 °C. Use q = nΔHfus for the phase change.
- Warm liquid water from 0 °C to 100 °C, then boil it at 100 °C. During boiling use q = nΔHvap.
- After vaporization finishes, further heat warms the steam. H₂O remains H₂O throughout: melting and boiling do not break the molecules into atoms.
About this model. Five equally wide diagram segments make the stages easy to explore; they do not imply equal energy or equal duration. The particles are a schematic, with no physical speed or size scale.