Question

The partial pressures of a mixture of gases are asfollows: oxygen, 210 mm Hg; nitrogen, 560 mm Hg;and carbon dioxide, 15 mm Hg. The total pressure ofthe gas mixture is 790 mm Hg. Is there another gaspresent in the mixture?

Answer 1

Partial pressure is the force which a gas exerts. The sum of the partial pressures in a mixture of all the gases equals the overall pressure.

The total pressure of the gas mixture is 790mm Hg.

If we sum all the partial pressures, we got:

Oxygen: 210mm Hg +

Nitrogen: 560 mm Hg +

Carbon Dioxide: 15 mm Hg

= 785 mmHg

As you can see, the sum of all the partial pressures is less than the total pressure. For this reason, there should be another gas present in the mixture whose partial pressure is 5 mm Hg, to make the total pressure be 790 mm Hg.