The mole fraction of He in a gaseous solution prepared from 3.0 g of He, 6.5 g of Ar, and 10.0 g of Ne is __________.
A)0.53
B)0.75
C)0.20
D)0.66
E)0.86

Question

Quizplus · Accepted Answer

The mole fraction of a component in a gaseous solution is equal to the number of moles of that component divided by the total number of moles of all components in the solution. The molar mass of He is 4.00 g/mol, the molar mass of Ar is 39.95 g/mol, and the molar mass of Ne is 20.18 g/mol. Therefore, the number of moles of He in the solution is 3.0 g / 4.00 g/mol = 0.75 mol, the number of moles of Ar in the solution is 6.5 g / 39.95 g/mol = 0.163 mol, and the number of moles of Ne in the solution is 10.0 g / 20.18 g/mol = 0.496 mol. The total number of moles of all components in the solution is 0.75 mol + 0.163 mol + 0.496 mol = 1.41 mol. Therefore, the mole fraction of He in the solution is 0.75 mol / 1.41 mol = 0.53.

The Mole Fraction of He in a Gaseous Solution Prepared