Question

A quantity of CO gas occupies a volume of 0.70 L at 0.90 atm and 318 K . The pressure of the gas is lowered and its temperature is raised until its volume is 2.6 L . Find the density of the CO under the new conditions.

Answer 1

Here is how to do it. Denisty is mass divided by volume (for gas densities we use L for volume) and you know the volume - 0.70 L. So what you have to do is to calculate the mass of CO from the initial set of conditions.

To do this use the ideal gas equation to find the number of moles of CO

PV = nRT so n = PV/RT = (0.9 x 0.70)/(0.0821 x 318)= 0.02413

from the number of moles (n) use the molar mass of CO to find the mass of CO = 0.02413 * 28 = 0.67564 g

as moles of gas will remain constant

Then calculate the density   d = m/V =0.67564g/2.6L = 0.26g/L