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

Jun 15, 2017

An example of $\text{phase equilibrium}$.

#### Explanation:

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

${H}_{2} O \left(l\right) r i g h t \le f t h a r p \infty n s {H}_{2} O \left(g\right)$

The extent of equilibrium is conveniently measured by the partial pressure of ${H}_{2} O \left(g\right)$. 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 $1 \cdot a t m$, and thus the conditions of $\text{normal boiling point}$ are specified.