[StillLearning]

Here's the question:

What is the density (in g/L) of hydrogen gas at 18.0 C and a pressure of 1645 psi ?

Here's what I tried:

First I converted C to K, then psi to atm.  Then, I chose an arbitrary number for the volume (1 liter) and plugged the numbers into the ideal gas law to get (111.9 atm)(1.00L)=n(.0821)(291K).  I solved for n and got 4.68 mol.  Then, I used the molar mass of hydrogen to calculate the grams and got 4.68 g.  Then, I put the mass over the volume to get 4.68 g/L, but this isnt the right answer.   

[nj_bartel]

Hydrogen is a diatomic gas

[StillLearning]

Thanks.