What does partial pressure refer to in a mixture of gases?

Partial pressure refers to the pressure exerted by an individual gas within a mixture of gases. In a gas mixture, each gas contributes to the total pressure in proportion to its amount. This concept is rooted in Dalton's Law of Partial Pressures, which states that in a mixture of non-reacting gases, the total pressure is equal to the sum of the partial pressures of each individual gas.

Understanding partial pressures is essential for various applications, including calculating the behavior of gases in different conditions, such as changes in temperature or volume. It plays a critical role in fields like chemistry, environmental science, and even medicine when considering how gases behave in biological systems.

Other aspects, such as the total pressure of all gases and average pressure in a closed system, do not define partial pressure. They represent different concepts related to the overall behavior of gases but do not pinpoint the individual contributions of specific gases in a mixture. The ratio of one gas to another is also distinct from partial pressure, which is a measure of the exerted force of each gas rather than a comparative measurement.