Question

A gaseous mixture contain 32.9 mol % He, 40.7 mol % N_{2} and 26.4 mol % Ar. Determine the composition of this mixture on a mass basis based on the molecular weight given: MW(He) = 4.003 , MW (N_{2}) = 28.02 MW(Ar) = 39.95​

Answer 1

The composition of the mixture on a mass basis are as follows:

• He = 131.70 g
• N2 = 1140.41 g
• Ar = 1054.68 g

number of moles = mass of substnce / molar mass

molar mass and molecular weight has equal numerical values therefore

Number of moles = mass of substnce / molecular weight

mass of substance = number of moles * molecular weight

the moles are expressed in percentage hence the total moles should be 100

check: 32.9 + 40.7 + 26.4 = 100

He

mass of substance = 32.9 * 4.003 = 131.6987 g

$N_{2}$

mass of substance = 40.7 * 28.02 = 1140.414 g

Ar

mass of substance = 26.4 * 39.95 = 1054.68 g