[tortor1489]

100 liters equals how many moles?
50 liters would equal how many molecules?
I don't remember this stuff

[Capuchin]

Depends on the substance.

Moles is a measure of number of molecules. Liters is a measure of what volume those molecules take up. The two are related by the molecular mass and the density of the material, so they are dependent upon the material.

[ebaines]

For gasses there is a relationship between moles and volume, known as the ideal gas law. One mole of an ideal gas at standard temperature and pressure ("STP" = 0 degrees C, 1 atmosphere pressure) occupies 22.4 liters of volume. Thus 100 liters of an ideal gas at STP is 100/22.4 = 4.46 moles. Multiply by Avogadro's number to get the number of molecules: 4.46 moles x 6.022 x 10^23 molecules/mole = 2.69 x 10^24 molecules.

If the temp and pressure are not STP, you can use the ideal gas law to determine how many moles there are in a given volume: PV = nRT, where P=pressure(Pa), V = volume (m^3), n = number of moles, R = gas constant, and T = temp in Kelvins. The value for R depends on the units you're using - two of the most common are:

R= 8.314J/Mol K = 8.314 Pa m^3/Mol K, and
R = 0.082057 L Atm/mol K.

[Capuchin]

Ah yes of course, then it depends on temperature and pressure.

What are you looking for? :)