Question

Use the References to access important values if needed for this question A sample of an unknown gas is found to have a density of 2.23 g/L at a pressure of 1.15 atm and a temperature of 42°C. Assume ideal behavior. The molar mass of the unknown gas is g/mol.

Answer 1

The pressure of the gas (P) = 1.15 atm

The density of the gas (d) = 2.23 g/L

The temperature of the gas (T) = 42 ^oC +273.15 = 315.15 K

For an Idea gas, the relation between pressure, molar mass, the density of the gas, and the temperature is as follows:

PM = dRT

Here, the pressure of the gas is P, the molar mass of the gas is M, the density of the gas is d, the universal gas constant is R, and the temperature in kelvin is T.

Rearrange the formula for molar mass as follows:

M = dRT /P

Substitute 2.23 g/L for d, 0.08206 L.atm/mol.K for P, 315.15 K for T, and 1.15 atm for P. Determine the molar mass of the gas as follows:

M = (2.23 g/L x 0.08206 L.atm/mol.K x 315.15 K) / 1.15 atm

M = 50.1 g/mol

Thus, the molar mass of the gas is 50. g/mol [2 S.F]