Question

A gas mixture is made by combining 5.2 g each of Ar, Ne, and an unknown diatomic gas. At STP, the mixture occupies a volume of 12.85 L. What is the molar mass of the unknown gas? molar mass: g/mol Identify the unknown gas. Oo, Och, OF, OH, ON,

Answer 1

Considering molar,

Molar mass of Argon (Ar) = 40 g/mol

Molar mass of Neon (Ne) = 20 g/mol

Molar mass of unknown molecule = x g/mol

Total volume = 12.85 L​​​​​

The total number of moles of Ar, Ne and unknown gas molecule in the gas mixture of 5.2 g,

=   $(\frac{5.2}{40}+\frac{5.2}{20}+\frac{5.2}{x}) mol$​​​​​

Total volume of these 3 gases at STP is

= ​​​​​​

,5.2 5.2 90+ 5.2 )mol x 22.4L/mol = 12.85L 20' x

  

5.2 5.2 12.85 40 + 20+ 7 = 559 = 0.574mol

  

0.394 32 = 0.574

5.2 = 0.574 - 0.39 = 0.184mol 2

5.29 184mol 1 =

Molar mass of the unknown gas = 28.26 g/mol

N2(Nitrogen mmolecule) has the molar masa 28 g/mol