Question

50% by mass of a 2.2 moles

mixture of He and Ar gasses .
Calculate the mole number of He
in the mixture?

Answer 1

Mol He in the mixture = 2

Further explanation

Given

50% by mass

2.2 moles of mixture

Required

The mole number of He

Solution

50% by mass⇒ mass of He : mass of Ar = 1 : 1

Mol He = 2.2 - mol Ar

mass He = mass Ar

mol x MW He = mol x MW Ar

(2.2-mol Ar) x 4 = mol Ar x 40

8.8 - 4 mol Ar = 40 mol Ar

8.8 = 44 mol Ar

mol Ar= 0.2

mol He = 2.2 - 0.2 = 2