Help on Finals Study Packet!!!!

[pussnboots]

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?

[pussnboots]

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? :?:

[Nick]

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

[Borek]

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

Best,
Borek

[GCT]

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.