Question

A gas has density 2.41 g/liter at 25°C and 770 mm Hg
Calculate its molecular mass. (R = 0.0821 L atm.mol-'K-1)​

Answer 1

Given : Density - 2.41 g/liter

Temperature - 25° C

Pressure : 770 mm Hg

R = 0.0821 L atm mol-¹K-¹

Find : Molecular mass of gas

Solution : Ideal gas equation with respect to density will be : PM = dRT. In the formula, P is pressure, M is molecular mass, d is density, R is gas constant and T is temperature.

Keeping the values in equation-

Pressure : 770 mm Hg = 1 atm

Temperature : 273 + 25 = 298 K

M = dRT/P

M = (2.41*0.0821*298)/1

M = 58.96 gram/mol

Thus, the molecular mass of gas is 58.96 gram/mol.