calculation of mEq from conc

debabrata · Probably a bot. Joined: 04 Nov 2005 Posts: 1

a medical textbook says "10 ml of 5% magnesium sulphate (MgSO4) provides about 4 mEq Magnesium"-- my calculation says it should be 8 mEq. i am flabergasted. also at the fag end of my knowledge in chem as i am studying medicine and followed by specialization in psychiatry for last 12 years. somebody please help.
debabrata

sdekivit · Regular Joined: 26 Jul 2005 Posts: 37 Location: Holland

the amount of equivalents is the amount of mols multiplied with the coefficient of the ionspecies mulitplied with the carge of the ion.

5% = 5g / 100 mL --> thus 10 mL contains 0,5 g MgSO4

--> 0,5 g MgSO4 is equal to 4,2 mmol

--> this is equal to 4,2 * 1 * 2 = 8,4 mEq MgSO4 (1 for the ionspecies Mg and 2 for the 2+-charge of Mg)

You didn't bring the charge into account Wink