At what pressure does the hydrocarbon C₂H₆ have a density of 2.50 g/L at 25.0 °C?

Answer 1

Molar mass C₂H₆ = 30 g / mole

If we assume we have 1 L of C2H6, and the density is 2.50 g / L we can find this in moles / L

2.50 g / L x 1 mol / 30 g = 0.0833 moles / L

Now use the ideal gas law to find the pressure

PV = nRT

P = nRT / V

P = (0.0833 mol)(0.0821 Latm/Kmol)(298K) / 1 L

P = 2.04 atm