A gas mixture, with a total pressure of 300. torr, consists of equal masses of Ne (atomic weight 20.) and Ar (atomic weight 40.). What is the partial pressure of Ar, in torr?
A)75 torr
B)100. torr
C)150. torr
D)200. torr
E)None of these choices are correct.

Question

Quizplus · Accepted Answer

According to Dalton's law of partial pressures, the partial pressure of a gas is equal to the total pressure times the mole fraction of that gas in the mixture. Since the gas mixture consists of equal masses of Ne and Ar, the mole fraction of each gas is 0.5. Therefore, the partial pressure of Ar is:
Partial pressure of Ar = (0.5)(300 torr) = 150 torr
So the correct answer is B.

A Gas Mixture, with a Total Pressure of 300