Partial pressure

Definition

Partial pressure is the pressure that a single gas in a mixture of gases would exert if it occupied the entire volume by itself. It is an essential concept for understanding gas mixtures and reactions in chemistry.

5 Must Know Facts For Your Next Test

1. Partial pressure is directly proportional to the mole fraction of the gas in the mixture.
2. Dalton's Law states that the total pressure of a gas mixture is equal to the sum of partial pressures of all individual gases.
3. Partial pressures can be used to calculate the amounts of reactants and products in gaseous reactions.
4. The partial pressure of a gas can be calculated using $P_i = X_i \cdot P_{total}$, where $P_i$ is the partial pressure, $X_i$ is the mole fraction, and $P_{total}$ is the total pressure.
5. In stoichiometry, partial pressures are useful for determining equilibrium constants involving gases.

Review Questions

• What does Dalton's Law state about partial pressures?
• How do you calculate the partial pressure of a gas in a mixture?
• Why is partial pressure important in gaseous reactions?

Related terms

Dalton's Law:

The law stating that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of individual gases.

Mole Fraction:

A ratio representing the concentration of one component in a mixture, defined as moles of component divided by total moles in the mixture.

Ideal Gas Law:

$PV=nRT$, an equation describing the state of an ideal gas where $P$ represents pressure, $V$ volume, $n$ moles, $R$ ideal gas constant, and $T$ temperature.