Investigation: heating and cooling curve of water

Aim: to investigate how the temperature of water changes with time during heating, and to identify the plateau at a change of state.

• Apparatus: beaker, water, ice, thermometer, hot plate, stopwatch.
• Method: record the temperature every 30 seconds from ice through to boiling.
• Plot temperature (y) against time (x) and describe the shape.
• The flat sections show energy going into the change of state, not into temperature.

• Plateau — the flat part of the curve during a phase change.
• Latent heat — energy absorbed during a change of state.