Dalton’s Law of Partial Pressures Calculator
💨 Gas Laws & Fluids. Use the Dalton’s law of partial pressures formula to find partial pressure, mole fraction, total pressure: pick the value you want, type the others, and the answer updates as you go.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Partial pressure | kPa |
| Mole fraction | no unit |
| Total pressure | kPa |
Worked example
Find the partial pressure when Mole fraction = 0.21, Total pressure = 101.3 kPa.
Using pA = xA × Ptotal: Partial pressure = 21.273 kPa.
Frequently asked questions
What is the formula for Dalton’s law of partial pressures?
pA = xA × Ptotal.
What do the letters stand for, and what units are used?
Partial pressure in kPa, Mole fraction, Total pressure in kPa.
How do you calculate partial pressure?
Put the values into pA = xA × Ptotal. For example, with Mole fraction = 0.21, Total pressure = 101.3 kPa, partial pressure = 21.273 kPa.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (partial pressure, mole fraction, total pressure) and fill in the others: it rearranges the formula for you.
