Question

Calculate the molar mass of a gas which has a density of 2.615 g dm-3 at 25oC and pressure of 101 kNm-2

Answer 1

P= 101 kN/m^2

= 101 kPa

= (101*1000) pa

= 101000 Pa

= (101000/101325) atm

= 0.9968 atm

T= 25 oC

= (25+273) K

= 298 K

density = 2.615 g/dm^3 = 2.615 g/L

Lets derive the equation to be used

we have below equation to be used:

p*V=n*R*T

p*V=(mass/molar mass)*R*T

p*molar mass=(mass/V)*R*T

p*molar mass=density*R*T

Put Values:

0.9968 atm * MM = density * 0.0821 atm.L/mol.K *298.0 K

MM = 64.2 g/mol

Answer: 64.2 g/mol