[Steve1956]

Ok here's the question, I just can't seem to get it. I'll put what I've tried so far too.

A mixture of Ne and Ar gases at 350 K contains twice as many moles of Ne as of Ar and has a total mass of 52.0 g. If the density of the mixture is 4.11 g/L, what is the partial pressure (in atm) of Ne?

so since it contains 2 times as many moles I was using an equation to solve for the # of moles of Ne. I did 2x(weight of Ne)+x(weight of Ar)=total mass, solving for x.

Then I wasn't really too sure where to go so I used the density to get the volume, 52g/x=4.11g/L, and then plugged in the numbers in PV=nRT, but i get the wrong answer.

Can you guys help me out or tell me where I am going wrong? Thanks!

[Yggdrasil]

Can you show the numbers that you from your calculations?  Your approach is correct, so you may be making some small mistake in the calculations.

Edit:  found the mistake.  In the calculation of the total volume, you need to use 3x, the total number of moles of gas.