what is PARTIAL PRESSURE?

[Zebra]

i heard this somewhere..

[Zebra]

got it! but don't know how we can be asked on this concept. hmmm

[Panicmode]

Partial pressure is the pressure that each respective gas exerts in a vessle containing more than one gas.

As we know, 1 mole of an ideal gas behaves exactly the same regardless of what it is made of. The partial pressure of a gas is the pressure it would exert if it was to occupy the same space by itself.

The total pressure of a container can be calculated by addition of the partial pressures of each respective gas.

[Bismuth]

P_total = P₁ + P₂ + P₃ + .... + P_n

The total pressure of a mixture of gases is just the sum of the pressures that each gas would exert if each gas was present alone.

The gases do not chemically interact with each other. For highschool chemistry, they often employ these types of questions with the involvement of water vapour (collecting a certain gas over water, for example). You don't want water pressure, so you would have to simply subtract it. It's a simple concept, but they can have trickier questions involving it.

Example of a question (taken from 1/2 Heinemann):

The pressure inside a gas cylinder is 800kPa. The cylinder contains 4.00 mol of nitrogen gas, 10.0 mol oxygen gas and 2.00 mol argon gas. What is the partial pressure exerted by the oxygen gas, in kPa?