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Topic: mole density  (Read 5078 times)

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Offline chubb87

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mole density
« on: January 30, 2010, 12:30:22 PM »
Hi,

I have to determine the mole density of CO2.
Given is the gasmixture of 0.1% CO2 and 0.9% N2 at 1000K and 1atm.

I tried to solve it with the ideal gas law:


p*V = n*Rm*T   ->  n/V = p/(Rm*T) = mole density c

and for the fraction CO2:
cCO2 = nCO2/V = pCO2/(Rm*T) = 1.2184 mol/m3 = 1.2184*10-3mol/l

Is that right?
Thank you in advance.
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Offline Borek

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Re: mole density
« Reply #1 on: January 30, 2010, 01:31:00 PM »
What is mole density?  :o
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Offline chubb87

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Re: mole density
« Reply #2 on: January 30, 2010, 01:38:05 PM »
I meant molar density.
It is used in a paper from the year 2000.
The symbol is N and the unit is mol/m3.
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Offline Borek

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Re: mole density
« Reply #3 on: January 30, 2010, 03:16:33 PM »
Judging from unit it looks like concentration, not density - density is usually mass/volume. Strange.
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Offline chubb87

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Re: mole density
« Reply #4 on: January 30, 2010, 05:59:32 PM »
Yes, normal (mass) density is mass/volume and this is molar density, which means mol/volume.
I suppose molar density and concentration are the same.
Anyway, does my calculation make sense?
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Offline Borek

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Re: mole density
« Reply #5 on: January 30, 2010, 06:05:31 PM »
What is value of pCO2?
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Offline chubb87

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Re: mole density
« Reply #6 on: January 30, 2010, 06:15:57 PM »
Because 0.1% is CO2, I used the partial pressure as 0.1atm, which is about 0.1bar.
So I used the formula xi = pi/p
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Offline Borek

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Re: mole density
« Reply #7 on: January 30, 2010, 06:59:29 PM »
Good thinking, wrong numbers.
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Offline chubb87

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Re: mole density
« Reply #8 on: January 30, 2010, 07:14:49 PM »
I just discovered a mistake in my posts: it is of course 0.1 = 10%, not 0.1%

But I get the same result as before...
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Offline Borek

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Re: mole density
« Reply #9 on: January 31, 2010, 03:18:21 AM »
Doesn't sound possible to me.
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