Question #72c10

1 Answer
Apr 18, 2014

When a substance is changing state, as it does during condensation, removing heat doesn't result in a change of temperature. The heat released is "hidden," or latent.

The heat that is released during condensation slows the particles of the vapor down to the point where the change of phase occurs. At this point, any heat lost by particles in the phase change is then absorbed by the particles that have already changed phase, keeping their temperature (the measurement of the average energy of the particles in the substance) the same. This occurs until the phase change is complete, and then the temperature change picks up again.

The same thing happens at fusion (freezing); the reverse happens in vaporization and melting.

The graph below shows the latent heat required or released during the phase changes of water: