RE: [Histonet] normal solutions question
Normality is the concentration of the reactive species. If the reactive
species is hydrogen ions, you have to look up (or memorize) the number of
hydrogen ions per molecule of acid.
If someone gives the formula of lactic acid as CH3CHOHCOOH, you are supposed
to know that only the last hydrogen dissociates in water and reacts with
hydroxide ions. Thus, 1 molar lactic acid is 1 normal. If the formula of
lactic acid is given as C3H6O3, you have to look up the structural formula.
Sulfuric acid is H2SO4. There are two dissociable hydrogens. Thus, 1 molar
sulfuric acid is 2 normal (or, better, 2 normal in hydrogen ions).
Phosphoric acid is H3PO4. There are three dissociable hydrogens. Thus 1
molar phosphoric acid is 3 normal in hydrogen ions.
Citric acid also has 3 dissociable hydrogens, and 1 molar citric acid is 3
normal in hydrogen ions. The molecular weight is 192 daltons per molecule
(or 192 grams per mole). 192 grams of citric acid in a liter of solution
would be a 1 molar or 3 normal solution. If you want a 1 normal solution,
you will need only 1/3 as much citric acid per liter. Thus, 64 grams of
citric acid in a liter of solution would be 0.333 molar or 1 normal, and 64
would be the "normal weight" of citric acid (assuming that you are concerned
with the normality of dissociable hydrogen, which is usually the case).
Allen A. Smith, Ph.D.
Professor of Anatomy
School of Graduate Medical Sciences
Miami Shores, FL
[mailto:firstname.lastname@example.org] On Behalf Of
Sent: Wednesday, January 14, 2004 2:54 PM
Subject: [Histonet] normal solutions question
Thank You guys for all the responses i have received...but im still STUCK i
don't understand how to come up with the positive valence, or number of
dissociable or replaceable hydrogen ions.....this is the number that i
molar weight with to get the normal weight....every problem i have worked
seem to be dividing by 2 and that doesn't make since to me.
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