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Integrating a concentration profile

 
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Jan8-13, 10:16 AM   #1
 

Integrating a concentration profile


Hello-

I have a diffusion profile, in which I plot the decrease in concentration versus distance of my sample. I am trying to find the increase in mass of the overall sample. How would I do this?

I have integrated the function and am wondering what type of information that would supply my. Units would be concentration*distance. moles*m
 
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Jan8-13, 12:44 PM   #2
mfb
 
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How are concentration of something and "mass of the overall sample" related?
If your diffusion (and concentration) is not one-dimensional, you should consider this in the integral.
"Moles" is not a concentration.
 
Jan9-13, 02:44 AM   #3
 
I did not actually plot the concentration. My diffusion profile consists of an initial amount of substance a in moles n(a) and plots it as a function of distance in the sample. so I am trying to figure out what information I get when I integrate this profile. moles*meters would be the units
 
Jan9-13, 08:08 AM   #4
mfb
 
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Integrating a concentration profile


Again, "moles" is not a concentration. Moles as a function of distance are meaningless, unless it means the total amount of substance between that point and some other point. In that case, I don't see any application of the integral.
 
Jan9-13, 09:01 PM   #5
 
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Concentration is usually expressed as moles per unit volume (e.g., moles/cc). The integral of this is moles/cm2. To get the total number of moles in the sample, you then need to multiply by the cross sectional area of the sample.
 
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