milliequivalent formula question


0Jun 16, '07 by mshultzQuote from GingerSuehttp://www.merck.com/mmpe/appendixes/ap1/ap1a.htmlthe formula used to convert millimoles to milliequivalents is
mEq = mmol/L X valence
How is this used when considering sodium?
Sodium's atomic weight is 23 mg,
therefore 23 mg of sodium is 1 mmol of sodium
a mmol of a substance is the atomic weight in milligrams
"The following can be used to convert between mEq, mg, and mmol:
mEq = mg/formula wt × valence = mmol × valence
mg = mEq × formula wt /valence = mmol × formula wt
mmol = mg/formula wt = mEq/valence
(Note: Formula wt = atomic or molecular wt.)"
So, for Sodium:
1 mEq = 23mg/23 (formula wt) x 1 (valence) = 1mmol x 1 (valence)
23mg = 1mEq x 23 (formula wt) /1 (valence) = 1mmol x 23 (formula wt)
1mmol = 23mg/23 (formula wt) = 1mEq/1 (valence)
Calcium has a formula weight of 40, and a valence of 2, so:
2 mEq = 40mg/40 (formula wt) x 2 (valence) = 1mmol x 2 (valence)
20mg = 1mEq x 40 (formula wt) /2 (valence) = 0.5mmol x 40 (formula wt)
1mmol = 40mg/40 (formula wt) = 1mEq/2 (valence)
40mg of Ca = 2 mEq
1mmol of Ca = 0.5 mEq
1 mEq of Ca = 20mg