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Unread 06/21/2007, 10:23 AM   #1
rachelcb80
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Join Date: Oct 2006
Location: Jackson, MS
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Converting mg/L into mEq/L

I've been searching online for how to do this but my head is starting to hurt. I've never been good at math and forget chemistry! I found a conversion formula but it was for Ca and you have to know the valence or something like that so I thought I'd try looking up "valence of CaCO3" but that didn't work. I probably wasn't even on the right track. This is what I was looking at;

milliequivalents per liter (meq/L) - meq/L is another method of expressing concentration, when the analytes are dissolved and disassociated in solution. meq/L is also equal to millimoles of charge per liter (mM+/L or mM-/L depending on valence). To calculate meq Ca/L from the reported value in mg/L, we must know something about calcium.


Calcium has a molecular weight of 40.08 grams/mole
Calcium has a valence of +2
The equivalent weight = (40.08grams/mole)/(2 equivalents/mole) = 20.04 grams/eq
To convert to mg/meq you simply multiply g/eq by 1000 mg/g and divide by 1000 meq/eq, thus g/eq = mg/meq
If your sample contains 30 mg Ca/L, what is the concentration in meq/L?

Meq Ca/L = (30 mg Ca/L)/(20.04 mg/meq) = 1.50 meq Ca/L

Anyways, I just want to know if you have alkalinity test results of 110 mg/L, what is that in meq/L? (I'd like to know how to solve the problem too for future reference)


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