The mole fraction of He in a gaseous solution prepared from 4.0 g of He, 6.5 g of Ar, and 10.0 g of Ne is .
A) 1.5
B) 0.61
C) 0.86
D) 0.11
E) 0.20

Question

Quizplus · Accepted Answer

To find the mole fraction of He, we need to first find the moles of each gas present in the solution.

moles of He = mass/molar mass = 4.0 g/4.003 g/mol = 0.999 mol
moles of Ar = 6.5 g/39.95 g/mol = 0.163 mol
moles of Ne = 10.0 g/20.18 g/mol = 0.495 mol

The total moles of gas present in the solution is:

0.999 mol + 0.163 mol + 0.495 mol = 1.657 mol

The mole fraction of He is:

moles of He/total moles of gas = 0.999 mol/1.657 mol ≈ 0.61

Therefore, the best choice is B.

The Mole Fraction of He in a Gaseous Solution Prepared