A vapour (British spelling) or vapor (see spelling differences) is a substance in the gas phase at a temperature lower than its critical point. This means that the vapour can be condensed to a liquid or to a solid by increasing its pressure without reducing the temperature.
For example, water has a critical temperature of 374 °C (647 K), which is the highest temperature at which liquid water can exist. In the atmosphere at ordinary temperatures, therefore, gaseous water (known as water vapor) will condense to liquid if its partial pressure is increased sufficiently.
A vapour may co-exist with a liquid (or solid). When this is true, the two phases will be in equilibrium, and the gas pressure will equal the equilibrium vapour pressure of the liquid (or solid).
Read more about Vapour: Properties, Vapour Pressure, Examples, Measuring Vapour, Vapours of Flammable Liquids
Famous quotes containing the word vapour:
“Thy great leaves enfold
The ancient beards, the helms of ruby and gold
Of the crowned Magi; and the king whose eyes
Saw the Pierced Hands and Rood of elder rise
In Druid vapour and make the torches dim....”
—William Butler Yeats (1865–1939)
“I had rather be a toad,
And live upon the vapour of a dungeon
Than keep a corner in the thing I love
For others’ uses.”
—William Shakespeare (1564–1616)
“O curse of marriage,
That we can call these delicate creatures ours
And not their appetites! I had rather be a toad,
And live upon the vapour of a dungeon
Than keep a corner in the thing I love
For others’ uses.”
—William Shakespeare (1564–1616)