Question

A mixture of CO₂ (g) and C₂H₆ (g) has a volume of 25.0 Liters at 35.0 ^oC, 20 psi. If there are a total of 22.704 grams of carbon in the mixture and the partial pressure of the CO₂ is 26.0 kPa greater than the partial pressure of the C₂H₆, what is the density of the mixture in grams per liter?

(Answer = 2.06 g/L )

Answer 1

mol of C = mass/MW = 22.704/12 = 1.892

PCO2 = 26 kPa + PC2H6

apply:

PV = nRT

n = PV/(RT)

n = (20/14.7)(25)/(0.082*(35+273))

n = 1.3467

total mol --> 1.3467

molar balance:

mol of CO2 + mol fo C2H6 = 1.3467

mol of C:

mol of CO2 + 2 mol of C2H6 = 1.892

mol of CO2 = 1.3467-mol of C2H6

1.3467-mol of C2H6 + 2 mol of C2H6 = 1.892

mol of C2H6 = 1.892/ (1.3467+2) = 0.5653

mol of CO2 = 1.3467-0.5653 = 0.7814

mass of C2H6 = mol*MW = 0.5653*30 = 16.959 g

mol of CO2 = 0.7814*44 = 34.3816 g

D = mass/V = (16.959 +34.3816 )/25 = 2.05 g/L