Question

What is the pressure of 2.50 moles of an ideal gas if it has a volume of 50.0 liters when the temperature is 300.0 K

Answer 1

Start with the ideal gas equation, PV=nRT PV=nRT and rearrange for pressure to get p=nRTV  p=nRTV . You have all the necessary variables in their proper units, so plug em' into the equation to solve for pressure in units of atmospheres.

P=(2.5 mol)(300 K)(0.08206 L atm K −1  mol −1 50.0 L =1.23 atm P=(2.5 mol)(300 K)(0.08206 L atm K−1 mol−150.0 L=1.23 atm

All that needs to be done now is converting atmospheres to mm Hg Hg .

1.23 atm∗760 mm Hg1 atm =935 mm Hg 1.23 atm∗760 mm Hg1 atm=935 mm Hg .

That value makes sense, since the original pressure in atmospheres was above 1, the pressure in mm Hg Hg will be above 760.