How Do You Calculate the Density of Hydrogen Gas in a Cylinder?

AI Thread Summary
To calculate the density of hydrogen gas in a cylinder, first determine the number of moles using the formula mass divided by molecular mass, yielding 2.31 moles for 4.62g of hydrogen. The volume is then calculated using the ideal gas law, resulting in approximately 0.0024 m³. The density is found by dividing the mass in kilograms (0.00462 kg) by the calculated volume, leading to a more reasonable density value. There is a clarification regarding the relative molecular mass of hydrogen, which is 1 for a single atom and 2 for H2 molecules. The discussion highlights a common confusion about molecular mass in gas calculations.
QueenFisher
ideal gases. what fun. please help!

i'm having problems getting sensible answers...

1.
a cylinder contains 4.62g of hydrogen at 17C and 2.32 x10^6 Pa
calculate number of moles.

actual mass/molecular mass= 4.62/2= 2.31
(relative molecular mass given as 2 in the question...is this right??)

calculate density of gas.
density=mass/volume

volume:
using pV=nRT
V=nRT/p
=2.31x8.31x(17+273) all divided by 2.32x10^6
=0.00239951...

density=4.62x10^3 (to make it into kg) divided by 0.00239951...

gives 1925393.101... kgm^-3
which seems awfully high.
i have another question but i'll put it in another thread before my computer crashes and i lose all of this.
 
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I think you'll find the RMM of Hydrogen is 1.
 
4.62g equals .00462kg NOT 4.62*10^3kg

should fix your answer
 
Hootenanny said:
I think you'll find the RMM of Hydrogen is 1.


well then either my physics teacher is wrong, or he was thinking of it in terms of H2 molecules. i did wonder when i read it if it was right, but i ended up with the right answer.
 

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