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?

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 class=


Answer :

Answer

720.9 mmHg

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

[tex]Atmospheric\text{ }pressure=P_{SVP}-P_{nitrogen}[/tex]

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

[tex]\begin{gathered} 742mmHg=21.1mmH-P_{nitrogen} \\ \\ P_{nitrogen}=742mmHg-21.1mmHg \\ \\ P_{nitrogen}=720.9\text{ }mmHg \end{gathered}[/tex]