Question

Density of a gas was found to be 5.59K at 27°C and 2 bar pressure.Calculate its molecular mass

Answer 1

Using the Ideal Gas Equation,

PV = nRT

P is the Pressure , V is the volume, n is the no. of moles, R is universal gas constant, and T is the temperature.

PV = Mass/Molar Mass × RT

P × Molar Mass = Mass/Volume × RT

∴ Density = PM/RT

P = 2 bar, Density = 5.59 L (It should be this only, not given), T = 300 K, R = 0.0831 L atm/mol K.

∴ 5.59 = 2 × M/(0.0831 × 300)

∵ M = 5.59 × 0.0831 × 300/2

∴ M = 69.68 g.

Hence, Molar mass of the gas is 69.68 g/mole.

Hope it helps.

Answer 2

Using the Ideal Gas Equation,

PV = nRT

P is the Pressure , V is the volume, n is the no. of moles, R is universal gas constant, and T is the temperature.

PV = Mass/Molar Mass × RT

P × Molar Mass = Mass/Volume × RT

∴ Density = PM/RT

P = 2 bar, Density = 5.59 L (It should be this only, not given), T = 300 K, R = 0.0831 L atm/mol K.

∴ 5.59 = 2 × M/(0.0831 × 300)

∵ M = 5.59 × 0.0831 × 300/2

∴ M = 69.68 g.