A mixture of gases behaves the same as a sample of a single gas. Since the gas laws apply to all ideal gases regardless of what the gas under consideration is, if gases are mixed, the gas laws should still apply. However, in a mixture of gases the gases may exert different pressures on the container. The pressure due to one gas in a mixture is called the partial pressure of the gas. The partial pressure is calculated directly from the given environmental conditions. The presence of the other gases is irrelevant. The sum of the partial pressures of all of the gases must be the same as the pressure exerted by a pure sample of a single gas of equivalent mass under the same environmental conditions. This result is known as Dalton's law of partial pressures and is expressed as
Example:
A gaseous mixture consists of 2 moles of carbon dioxide, 1 mole of carbon monoxide, and 1 mole of ozone. The gas occupies a 20L container at 400K. Find the partial pressure of each gas and verify that the sum of the partial pressures equals the equivalent pressure of a pure sample under the same conditions.
