Posted by Eric on .
You have a 22L cylinder of helium at a pressure of 150atm and a temperature of 31C. How many ballons can you fill, each with a volume of 5.0L, on a day when the atmospheric pressure is 755mmHg and the temperature is 22C?
I know I use PV=nRT, but what numbers do I plug in and why couldn't I use p1v1/t1=p2v2/t2?

Chemistry 
DrBob222,
You may use the other formula if it's easier for you and you plug in the right numbers. DON'T use 5.0 L as V2 and you must change one of the pressures to make the same unit (150 atm must be changed to mm or 755 mm must be changed to atm). And T must be in Kelvin.
For PV = nRT
150 atm = P
V = 22 L
n = ??
R = 0.08205
T = 31 + 273 = 304.
Then use PV = nRT again.
P = 755 mm = 755/760 = ?? atm.
V = solve for this.
n = use from calculation above.
R = same constant as above.
T = 22 + 273 = 295
Then use the volume from this last calculation to determine how many 5.0 L balloons can be filled.