- Critical temperature: The temperature above which a gas cannot be liquefied regardless of the amount of pressure applied. (K/°C). At this point the specific latent heat is zero, as no further energy is required to complete the change in state of the substance.
- Critical pressure: The minimum pressure required to cause liquefaction of a gas at its critical temperature. (kPa/Bar)
- The latent heat of vaporisation is the heat energy required to change the state of a substance from liquid to vapour.
- At its critical temperature, a liquid will change spontaneously into vapour without heat being required. In other words, the latent heat of vapourisation is zero
The Lay Medical Man 