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Topic: ideal gas law help  (Read 2127 times)

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Offline johnnyjohn993123

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ideal gas law help
« on: December 16, 2014, 09:00:46 AM »
Six grams of He gas are pumped into a 0.50-L cylinder at 60°C.  What is the pressure of the gas in the cylinder.?

My attmeps :
v=0.50L
n= 1.50 mol  T= 333K

P= (1.50× 333 × 0.08206 )÷ 0.50

P= 82.0 atm

Is this correct coz I think it is very high 😵???

Offline Arkcon

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Re: ideal gas law help
« Reply #1 on: December 16, 2014, 09:09:14 AM »
I would put in the units at each step for each parameter, especially for R.  This may help you keep track of things you may have left out of your current working.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline mjc123

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Re: ideal gas law help
« Reply #2 on: December 16, 2014, 10:59:17 AM »
Do a quick order-of-magnitude estimation. You know (I hope) that 1 mol of gas at 1 atm and 298K occupies 24L, so 1.5 mol would occupy 36L. 0.5L is 1/72 of this volume, so the gas would have to be compressed to 72 atm. So 82 atm doesn't look unreasonable for the pressure at a somewhat higher temperature.

Offline Arkcon

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Re: ideal gas law help
« Reply #3 on: December 16, 2014, 11:14:30 AM »
Do a quick order-of-magnitude estimation. You know (I hope) that 1 mol of gas at 1 atm and 298K occupies 24L, so 1.5 mol would occupy 36L. 0.5L is 1/72 of this volume, so the gas would have to be compressed to 72 atm. So 82 atm doesn't look unreasonable for the pressure at a somewhat higher temperature.

I have to give you a +1 for this tip.  This is an important trick to employ during an exam.  Be able to ballpark your result, before you move on.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

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