# A sample of chlorine gas is collected by water displacement at 23°C. If the atmospheric pressure is 751 torr, what is the partial pressure of the chlorine?

May 9, 2016

A gas collected over water, is saturated with respect to water vapour, which must be taken into account.

#### Explanation:

${P}_{\text{collected}}$ $=$ ${P}_{G a s} + {P}_{{H}_{2} O}$

${P}_{{H}_{2} O} \cong 20 \cdot m m \cdot H g$ at $20$ ""^@C.

So ${P}_{G a s}$ $=$ $731 \cdot m m \cdot H g$

$\text{SVP}$, $\text{the saturated vapour pressure}$ is tabulated for a range of temperatures, and values should have been included in the question.