Question

A gas mixture is made by combining 5.4 g each of Ar , Ne , and an unknown diatomic gas. At STP, the mixture occupies a volume of 69.03 L. What is the molar mass of the unknown gas

Answer 1

Answer:

The unknown gas is H2

Explanation:

Step 1: Data given

A mixture contains:

5.4 grams of Ar

5.4 grams of Ne

5.4 grams of X2

Molar mass of Ar = 39.95 g/mol

Molar mass of Ne = 20.18 g/mol

Step 2: Calculate moles of gases

.Moles of Ne = 4.5grams /20.18 g/mol = 0.223 moles

Moles of Ar= 4.5 grams /39.95 g/mol = 0.113 moles

Step 3: Calculate volume of gases

Volume of Ne =22.4 * 0.223 = 5

Volume of Ar =22.4 * 0.1525 = 2.53 L

Volume of unknown gas = 69.03 - 5 - 2.53 = 61.5 L

Step 4: Calculate moles of unknown gas

Moles of unkown gas =61.5/22.4 = 2.75 moles

Step 5: Calculate molar mass of unknown gas

Molar mass = mass / moles

Molar mass = 5.4 grams /2.75 moles ≈ 2 g/mol

The unknown gas is H2