Question

An unknown noble gas has a density of 5.84 g dm-3 at STP. Calculate its molar mass, and so identify the gas.

Answer 1

The noble gas is Xenon and its molar mass is 131 g/mol.

What is the molar mass of the noble gas?

The molar mass of the noble gas is determined as follows;

Let molar mass of unknown gas be M, and mass of gas be m

Density of the noble gas, ρ = 5.8 g/dm³

density = m/V

At STP;

• temperature, T = 273.15 K
• pressure, P = 1 atm
• molar gas constant, R = 0.0821 L.atmK⁻¹mol⁻¹

From ideal gas equation:

PV = nRT

where n = m/M

PV = mRT/M

M = mRT/PV

M =  0.0821 * 273.15 * 5.84/1

Molar mass of the noble gas = 131 g/mol

The noble gas is Xenon which has molar mass approximately equal to 131 g/mol.

Learn more about molar mass at: brainly.com/question/837939

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