A sample of water in a sealed flask at 298 K is in equilibrium with its vapor. What is this is an example of?

1 Answer
Jun 15, 2017

Answer:

An example of #"phase equilibrium"#.

Explanation:

For a given temperature, a condition of equilibrium exists between gaseous water molecules and the condensed phase, i.e.

#H_2O(l) rightleftharpoonsH_2O(g)#

The extent of equilibrium is conveniently measured by the partial pressure of #H_2O(g)#. And these so-called vapour pressures are extensively tabulated:

See this site. As seen on the site, even ice possesses some small vapour pressure. Liquid water expresses a vapour pressure that increases logarithmically with temperature; at #100# #""^@C#, water expresses a vapour of #1*atm#, and thus the conditions of #"normal boiling point"# are specified.