Partial pressure

Definition

Partial pressure is the pressure exerted by a single component of a mixture of gases. It is proportional to its mole fraction in the gas mixture and the total pressure of the mixture.

5 Must Know Facts For Your Next Test

1. The partial pressure of a gas in a mixture can be calculated using Dalton's Law: $P_i = x_i P_{\text{total}}$, where $P_i$ is the partial pressure, $x_i$ is the mole fraction, and $P_{\text{total}}$ is the total pressure.
2. Partial pressures are additive; thus, the sum of all partial pressures in a gas mixture equals the total pressure.
3. In an ideal gas, partial pressures can also be related to temperature and volume using the Ideal Gas Law: $P V = nRT$.
4. In respiratory physiology, partial pressures are crucial for understanding gas exchange in lungs.
5. The concept of partial pressure helps explain phenomena like why water boils at lower temperatures at high altitudes due to lower atmospheric pressure.

Review Questions

• How do you calculate the partial pressure of a gas in a mixture?
• What law states that the sum of all partial pressures equals the total pressure?
• Why are partial pressures important in understanding human respiration?

Related terms

Dalton's Law: States that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of individual gases.

Ideal Gas Law: $PV = nRT$, which relates pressure (P), volume (V), amount (n), ideal gas constant (R), and temperature (T).

Mole Fraction: The ratio of moles of one component to the total moles in a mixture. Used to determine partial pressures.