Partial Pressure and the Ideal Gas Law

The ideal gas law, PV=nRT is independent of the kind of gas. In other words, the pressure exerted by a given number of ideal gas particles is the same whether the sample consists of all one type of particle or a mixture of different kinds of particles.

Therefore, the pressure exerted by a mixture of gases can be expressed as follows:

Ptotal=(n1+n2+n3+⋯)RTV=ntotalRTV

partial pressure is the pressure exerted by just one type of gas in a mixture. A partial pressure is calculated using only the number of moles of that particular gas, instead of the total number of moles:

P1=n1RTV, P2=n2RTV, P3=n3RTV,etc.

The sum of the partial pressures is equal to the total pressure in the mixture:

Ptotal=P1+P2+P3+⋯

Air is about 78.0% nitrogen molecules and 21.0% oxygen molecules. Several other gases make up the remaining 1% of air molecules.  What is the partial pressure of nitrogen in air at atmospheric pressure (1 atm)? Assume ideal behavior.

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Posted on November 20, 2013, in Question and tagged , , , , , , , , , , . Bookmark the permalink. 1 Comment.

1. .78 atm

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