Dalton's Law of Partial Pressures, or Dalton's Law, states that the total pressure of a gas in a container is the sum of the partial pressures of the individual gases in the container. Here is a worked example problem showing how to use Dalton's Law to calculate the pressure of a gas.
Review Dalton's Law
Dalton's Law of Partial Pressures is a gas law that can be stated:
- Ptotal = P1 + P2 + P3 +… Pn
where P1, P2, P3, Pn are the partial pressures of the individual gases in the mixture.
Example Dalton's Law Calculation
The pressure of a mixture of nitrogen, carbon dioxide, and oxygen is 150 kPa. What is the partial pressure of oxygen if the partial pressures of the nitrogen and carbon dioxide are 100 kPA and 24 kPa, respectively?
For this example, you can simply plug the numbers into the equation and solve for the unknown quantity.
- P = Pnitrogen + Pcarbon dioxide + Poxygen
- 150 kPa = 100 kPa + 24 kPa + Poxygen
- Poxygen = 150 kPa - 100 kPa - 24 kPa
- Poxygen = 26 kPa
Check your work. It's a good idea to add up the partial pressure to make sure the sum is the total pressure!