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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: !!! on February 29, 2008, 03:29:29 PM

Title: Balancing and Stoichiometry
Post by: !!! on February 29, 2008, 03:29:29 PM
I need help on this problem:
"If maleic acid could be represented by the formula H2Ma, write the two balanced chemical equations for maleic acid’s reaction with NaOH in the space below (be sure to include states of matter).  Show the sequential neturalization of each acidic proton."
Is it correct if I have H2Ma + NaOH --> MaNa + H3O?
I have trouble putting down what the products are.
Title: Re: Balancing and Stoichiometry
Post by: Arkcon on February 29, 2008, 04:01:46 PM
Is it correct if I have H2Ma + NaOH --> MaNa + H3O?
I have trouble putting down what the products are.

That's wrong for 3 different reasons.  First off H3O isn't a compound.  Yes we generalize the hydronium ion as H3O, but it really doesn't happen.  Anyway H3O is not the product of neutralization.  The products are not charge balanced.

I don't see the states of matter anywhere.  Not really critical, but the question does ask for it, might as well put them in.

They want neutralization sequentally, one proton at a time, you're showing the end.

Is this MaH2 throwing you off.  It really is the same as H2SO4 -- they've just switched the abbreviation of the word for maleic with the SO4-2 anion.
Title: Re: Balancing and Stoichiometry
Post by: ARGOS++ on February 29, 2008, 04:11:20 PM
Dear !!!;

Maybe you forgot that you changed the charge from Na–Ion in your reaction from +1 to +2, but similar (not for Na!) is “only” possible for a Red-Ox-Reaction, and not in a Neutralisation, where the Ions must keep their Charge, except they build a “neutral” Product like water.

Hint: As a “normal Proton-” Acid the MaH2 finally spends its Protons and survives as Ma2- .

I hope it may help you to do the first Steps.

Dear Arkcon: Maleic Acid is not the same as H2SO4, but can, in this particular case, be handled in quite similar manner.


Good Luck!
                    ARGOS++

Title: Re: Balancing and Stoichiometry
Post by: Arkcon on February 29, 2008, 09:16:12 PM

Dear Arkcon: Maleic Acid is not the same as H2SO4, but can, in this particular case, be handled in quite similar manner.

True enough, maleic acid is a weaker acid than sulfuric, but like you say, the rules for the deprotonation of the maleate anion are the same for the sulfate anion.

This appears to be a running theme: Students get a question regarding a neutralization of an organic acid and come up with some totally inappropriate reactions.  I'm looking for a simple way to communicate carboxylic acids ionizing into H+ and organic anion.  The O.P. is lucky the question spells it out, compared to these other unfortunates:

http://www.chemicalforums.com/index.php?topic=22025.msg84244#msg84244

http://www.chemicalforums.com/index.php?topic=22703.msg86955#msg86955