How many molecules of neon are associated with a 75*L volume of neon gas?

1 Answer
May 16, 2016

The question should have specified a temperature. I am going to assume that the gas is at room temperature, 298*K.

Explanation:

We know that at room temperature and pressure, 1 mol of ideal gas occupies a volume of 25.4*L.

We assume (reasonably) that Ne behaves ideally.

Thus the number of moles of Ne = (75*L)/(25.4*L*mol^-1) ~= 3*mol.

But by definition, 1*mol of stuff possesses 6.022xx10^23 individual items of that stuff. If you can grasp this concept, it will save you a ton of angst.

Thus "Molecules (atoms) of neon" = (75*L)/(25.4*L*mol^-1)xx6.022xx10^23" neon atoms per mole"

~=18xx10^23 " neon atoms".

What is the mass of this quantity of neon gas?

(Neon gas is a monatomic molecule).

See also here.