Question

What is the density of ethane gas, C2H6, at 993 mm Hg and 40.5°C?

Answer 1

P= 993 mm Hg

= (993/760) atm

= 1.3066 atm

T= 40.5 oC

= (40.5+273) K

= 313.5 K

Molar mass of C2H6 = 2*MM(C) + 6*MM(H)

= 2*12.01 + 6*1.008

= 30.068 g/mol

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:

1.306578947368421 atm * 30.068 g/mol = density * 0.0821 atm.L/mol.K *313.5 K

density = 1.53 g/L

Answer: 1.53 g/L