ELIF the difference between smoke and vapor.
In: Chemistry
None of the other definitions of vapour are correct here (so far). A vapour is a substance in the gaseous state but below its critical temperature.
The definition of critical temperature is the temperature above which a substance cannot be returned to the liquid phase by application of pressure.
This means that I can heat a substance, water for example, and I can turn it into a gaseous substance (steam) but this is still a vapour – not a gas. With application of enough pressure, i can return the steam to the liquid phase, even at temperatures above 100C.
However, above a temperature of 374C (the critical temperature of water), application of pressure will *_never_* return steam to the liquid phase. For this reason, at this temperature and above, steam is truly a gas and not a vapour.
Latest Answers