Help on Finals Study Packet!!!!
 

If you have two baloons of equal volume at the same temperature and pressure, one containing helium and one containing methane, how do their masses compare?

Another question: What volume would occupy .100 moles of oxygen gas at STP? What about two moles?



And What are the STP conditions in relation to volumes of gases? :?:

you only need this:

p*V=n*R*T

p.. pressure
V.. Volume
n.. moles of gas
R.. Gasconstant
T.. temperature

all in SI

n = m/M where as M is g/mol and m is g

Use pV = nRT outside of STP. At STP one mole of any gas has 22.4L. Always.

Best,
Borek

The problem suggests equimolar amounts of the two gases, however their masses will differ since the molar mass is not the same.

PV=nRT

n=PV/RT, n=moles

molar mass=grams/mole

thus you have n x (Mhelium) and n x (Mmethane)=mass helium and methane respectively, where M=molar mass.

The ratio of masses turns out to be the ratio of molar masses.