Question

what is the mole fraction of neon in a mixture that contains 0.628 g of helium, 11.491 g of neon, and 7.613 g of argon?​

Answer 1

Answer:

0.2

Explanation:

Given parameters:

Mass of helium = 0.628g

Mass of neon = 11.491g

Mass of argon = 7.613g

Unknown:

Mole fraction of neon = ?

Solution:

The mole fraction of an element is the number of moles of that element to the total number of moles in the gas mixture.

We need to calculate the number of moles of each element first;

 Number of moles  = $\frac{mass}{molar mass}$

Molar mass of Helium = 4g/mol

Molar mass of Neon = 20g/mol

Molar mass of Argon = 40g/mol

Number of moles of He = $\frac{0.628}{4}$ = 0.16moles

Number of moles of Ne = $\frac{11.491}{20}$ = 0.58moles

Number of moles of Ar = $\frac{7.613}{40}$ = 0.19moles

Total number of moles = 0.16moles + 0.58moles + 0.19moles = 0.93moles

Mole fraction Neon = $\frac{0.19}{0.93}$  = 0.2