DAT DESTROYER Concept - Normalization/Neutralization

[Felix24]

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For questions about neutralization and converting molarity to normality.. how can you determine how many H+ an acid with a "complex structure" gives off? Obviously I know how many H+ dissociate for strong acids and simple weak acids (polyatomic, HF, etc.) but what if it's unclear how many hydrogens can dissociate? For example, in DAT Destroyer question, there was a problem that dealt with neutralizing citric acid (H3C6H5O7) with Ba(OH)2 strong base. The concepts and calculations all make sense and are pretty simple. However. in the question, the catch was that I didn't know how many hydrogens dissociated from citric acid (H3C6H5O7). I guessed 3 because they seemed the most reasonable and it ended up being right. However, if I picked 8 H+... I would've been screwed.

Any help or advice would be greatly appreciated.

 

[Hygienist]

HCl would dissociate into H+ and Cl-
H2SO4 into 2H+ and SO42-

so u can tell from the molecular formula, if it has 2H than 2, if 3 than 3 and so forth.

In a neutralization reaction # of moles of acid= # of moles of base so if one is given u can figure the other one out.

Normality is Molarity * number of Oh- or H+ given off.
So what is the normality of 3.0M H2SO4?
it is 3*2=6.
and then to find base normality or volume (Nacid)(Vacid)=(Nbase)(Vbase)
N= normality and V=volume

Hope this helps!

 

[Felix24]

Thanks for the reply! Everything you said holds true, however, my question was more so... how can you tell how many H+ dissociate from an acid if they give you something a little more complicated than the obvious acids..... for example, H3C6H5O7?

HCl would dissociate into H+ and Cl-
H2SO4 into 2H+ and SO42-

so u can tell from the molecular formula, if it has 2H than 2, if 3 than 3 and so forth.

In a neutralization reaction # of moles of acid= # of moles of base so if one is given u can figure the other one out.

Normality is Molarity * number of Oh- or H+ given off.
So what is the normality of 3.0M H2SO4?
it is 3*2=6.
and then to find base normality or volume (Nacid)(Vacid)=(Nbase)(Vbase)
N= normality and V=volume

Hope this helps!

 

[ttpharm]

Thanks for the reply! Everything you said holds true, however, my question was more so... how can you tell how many H+ dissociate from an acid if they give you something a little more complicated than the obvious acids..... for example, H3C6H5O7?

Its not a strong acid nor a strong base. It's not gonna fully associate. You're going to have to use its Ka.

 

[circa86]

this topic is bringing back my worst memories of gchem! just wait til you get to molten electrolysis, that's a real hoot

 

[chill45]

It would seem as though the pattern would be that the hydrogens that would dissociate are always first in the molecular formula. As you should know Destroyer is much tougher than the real exam. They most likely would give you something like sulfuric acid just to see if you know the difference in normality and molarity.