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

1 Answer
anor277
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.

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