So I believe that you are going to be using the formula PV = nRT and you will be solving for moles. You have everything you need for this formula: P = 170 mm hg **dont forget to change into atm V = .500 L R = gas constant (8.314 J / mol) T = 25.0 C + 273 = temperature in Kelvin Now it is just plug and chug I hope this helped! Have a fantastical day, Em
