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Hydrogen gas liquid equation 
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#1
Mar2205, 07:35 PM

P: 21

If 277 L of LIQUID hydrogen has a mass of 19.7 kg, what volume will this amount of hydrogen occupy as a GAS at 25 degrees celcius and 1 atm?
Is there some kind of equation that I can use to make this problem easier? THANKS! 


#2
Mar2205, 07:42 PM

P: 274

PV = nRT
You'll use this equation for almost every gas problem. R (idealgas constant) = 0.0821 Latm/moleK V = volume (L) P = pressure (atm) n = amount (moles) T = temperature (K) V = nRT/P You need to convert the 19.7 kg H2 to moles H2 and the 25 C to Kelvin. If you need more help, go ahead and ask. 


#3
Mar2205, 07:51 PM

P: 21

Do you have to take into account the hydrogen beginning as a LIQUID and ending as a GAS?



#4
Mar2205, 07:54 PM

P: 274

Hydrogen gas liquid equation
No because when you go from a liquid to a gas, the number of moles of H2 will still stay the same and therefore you can predict the volume.



#5
Mar2205, 08:01 PM

P: 21

When converting 19.7 Kg to moles would you use H2 (being 2.0158g) or just H (being 1.0079g)?



#6
Mar2205, 08:03 PM

P: 274

Good question. Always use the diatomic molecule...so H2.



#7
Mar2205, 08:07 PM

P: 21

Thanks for your help. So if i have done things right my answer should be close to 2.39 X 10^5 L



#8
Mar2205, 08:12 PM

P: 274

Yes I got a similiar answer. By the way, what value are you using for R? 0.0821 or something more precise?



#9
Mar2205, 08:15 PM

P: 21

For this problem I just used 0.0821, but usually I use 0.082057



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