How is partial pressure related to mole fraction?

1 Answer
anor277
Aug 2, 2017

The partial pressure exerted by a gas in a mixture is directly proportional to its mole fraction........This is an experimental result, known since the time of Dalton, who formulated the following expression.

Explanation:

The total pressure, #P_"total"#, is the SUM of the individual partial pressures, #P_1, P_2, P_3............#.

#P_1=(n_1RT)/V#; #P_2=(n_2RT)/V#, #P_3=(n_3RT)/V#............where #n_1#, #n_2..........n_n# are the molar quantities of each component.

#P_"Total"=(RT)/V{n_1 + n_2 + n_3+.........n_n}.#

And thus #P_1# #=# #(RT)/V{n_1/(n_1+n_2+n_3.............+n_n)}#...

and #P_n# #=# #(RT)/V{n_n/(n_1+n_2+n_3.............+n_n)}#...

And thus the partial pressure, #P_1#, is proportional to the mole fraction of #n_1#. The constant of proportionality is #(RT)/V#.

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