Dalton’s law of partial pressures says:
In a mixture of non-reacting gases, the total pressure is equal to the sum of the pressures that each gas would exert if it were alone in the container.
- Each gas in the mixture behaves independently, as if the others are not present.
- The pressure contributed by each gas is called its partial pressure.
Example:
If oxygen, nitrogen, and carbon dioxide are in a container, then:
Total pressure = Pressure of O₂ + Pressure of N₂ + Pressure of CO₂
Applications of Dalton’s law:
- Breathing gases – In scuba diving, the total pressure underwater is the sum of the partial pressures of oxygen and nitrogen.
- Gas collection over water – When gases are collected, water vapor contributes its partial pressure, which must be accounted for.
- Industrial gas mixtures – Used in preparing and analyzing mixtures like medical oxygen or anesthesia gases.
In simple words:
Dalton’s law adds up the pressures of all gases in a mixture to get the total pressure.