Ok so the problem is to find the density of carbon monoxide at 200 degrees K and 3.0 atm. So I know that the formula for density is D= mass(g)/volume (mL), so the mass i know already is 28.01 (by adding the molar masses of Carbon and Oxygen). To find the volume in mL, i used the equation PV=nRT, changing it to V=nRT/P to use it to find volume. So it read V=.0821*200K/3.0atm. When i solved it I got 5.473 as the volume in Liters. To convert this to milliliters, i multiplied by 1000, and got 5473.33 mL. Plugging this back into the original equation I got D= 28.01g/5473.33mL, and thus D=.00512g/mL. I just wanted to make sure my answer and procedure were correct...would someone please let me know? thanks so much!