A sample of O2 gas at a given temperature and pressure has a density of 1.30 g L-1. What is the density of gaseous propane (C3H8) under the same conditions?

Density is a value for mass, such as kg, divided by a value for volume, such as m3. Density is a physical property of a substance that represents the mass of that substance per unit volume. For gases we use the ideal gas equation to solve for density. We do as follows:

PV = nRT

PV = mRT / MM

Density = m/V = PMM / RT

From the conditions given of the O2 system we can determine P/RT as follows:

P/RT = density / MM = 1.30 / 32

P/RT = 0.0406

density of propane = 0.0406 x 44.11 = 1.79 g/L