How do you calculate the partial pressure of a gas in a mixture?

The correct method to calculate the partial pressure of a gas in a mixture is to multiply the gas's fraction (expressed as a decimal) by the total pressure of the mixture. This approach is grounded in Dalton's Law of Partial Pressures, which states that in a gas mixture, each gas exerts a pressure independently of the others, and the total pressure is the sum of the individual partial pressures.

To perform this calculation, you first convert the gas's percentage into a decimal (for example, 20% becomes 0.20) and then multiply this decimal by the total pressure of the gas mixture. This product gives you the partial pressure of that specific gas within the mixture. This method effectively accounts for the contribution of each gas to the overall pressure, enabling accurate predictions and assessments in clinical or environmental settings.

Understanding this calculation is crucial in various applications, such as respiratory therapy, scuba diving, and managing anesthetic gases, where knowing the partial pressures helps ensure safe and effective gas administration.