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Topic: Which solutions can have several normality values?  (Read 2120 times)

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Offline Xenonman

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Which solutions can have several normality values?
« on: April 08, 2014, 10:14:45 PM »
Hello all ;D
I just figured how annoying normality is. To get the full picture, I want to gather the names of as many solutions that have the same molarity, but different normality depending on the reaction they are used.
So far, I could think of Fe+3 ion, which could react to form either Fe+2 or Fe(s), thus having at least two normalities and one molarity. Same with copper.
The other one is H2Y-2: One could treat is as an usual acid or base (two acid/base sites per molecule), or use it for a typical complexometric titration (one complex is formed by one molecule). This gives at least two normalities and one molarity.

But I am sure there are examples I can't even think of. That's when all of you come in.
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Offline Borek

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Re: Which solutions can have several normality values?
« Reply #1 on: April 09, 2014, 02:53:47 AM »
H2SO4 (acid/base, BaSO4 precipitation).

Pb2+ (precipitation of chloride, precipitation of sulfate)

MnO4- (three different values for oxidations in acidic, neutral and basic solutions)

And so on.
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Offline Xenonman

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Re: Which solutions can have several normality values?
« Reply #2 on: April 09, 2014, 08:38:15 PM »
H2SO4 (acid/base, BaSO4 precipitation).
I was taught sulphuric has two acid sites, and gets its two protons removed by bases and Ba2+, so its normality should be the same for both reactions.
Pb2+ (precipitation of chloride, precipitation of sulfate)
Same thing here. Different stoichiometry, but same amount of positive charges and thus same normality.


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Offline Arkcon

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Re: Which solutions can have several normality values?
« Reply #3 on: April 09, 2014, 08:48:00 PM »
Xenonman:, you've made the same mistake twice in both postings.  Just because sthe sulfate ion is 2-, doesn't mean it interacts twice, the same as two H+.  Likewise, the Fe2+ and Fe3+ don't enter into discussions of normality and molarity.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Xenonman

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Re: Which solutions can have several normality values?
« Reply #4 on: April 23, 2014, 11:30:32 PM »
Back from the dead.

As far as I understand, IUPAC mentions the viability of using equivalents for solutions part of redox reactions. Here: http://goldbook.iupac.org/E02192.html.
And since equivalents are viable, and normality relies on equivalents, normality for redox should be a valid and archaic way of expressing concentration.
Honeste vivere, alterum non laedere, suum cuique tribuere.

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