A gas occupies a volume of 256mL at a pressure of 250torr at 32 degrees Celsius. Calculate the pressure (in atmosphere)if the volume is reduced to 156mL and the temp is increased to 62 degrees Celsius. I really need the formula that I would be using. I am confused because using PV=nRT there is no moles being given here.

Question

A gas occupies a volume of 256mL at a pressure of 250torr at 32 degrees Celsius. Calculate the pressure (in atmosphere)if the volume is reduced to 156mL and the temp is increased to 62 degrees Celsius.  I really need the formula that I would be using.  I am confused because using PV=nRT there is no moles being given here.
I surely would appreciate it.  THanks!

DrBob222 · Answer

Two ways to do it.
Use PV = nRT for the first set of conditions and solve for n, then redo PV = nRT, use the n from above and the new conditions, and solve for pressure.

Second way is to use
(P1V1/T1) = (P2V2/T2)
The second way is a little shorter since you cut out the solving for n step.

Sue · Answer

Thanks! I knew the formula but wasn't quite sure if i convert mL to L in the formula. I know that I must covert C to K and Torr to Atm for the equation.

Anonymous · Answer

.628 atm