Question

A sample of nitrogen gas is collected over water at a temperature of 23 C. What is the pressure of the nitrogen gas if the atmospheric pressure is 742 mm Hg?

Answer 1

720.9 mmHg

Step-by-step explanation

Gas collected over water must always account for the saturated vapor pressure.

Note that the saturated vapor pressure of water at 23 °C = 21.1 mm Hg.

Therefore atmospheric pressure is

`Atmospheric\text{ }pressure=P_(SVP)-P_(nitrogen)`

The atmospheric pressure given = 742 mmHg, Psvp = 21.1 mmHg, thus, we

`\begin{gathered} 742mmHg=21.1mmH-P_(nitrogen) \\ \\ P_(nitrogen)=742mmHg-21.1mmHg \\ \\ P_(nitrogen)=720.9\text{ }mmHg \end{gathered}`