[davon806]

Hi,I am doing some molarity calculation.One of the questions mention a compound:
KH3(C2H4)·2H2O,
and it is used to neutralize NaOH
I have never heard a such compound before.
Obviously it is an acid
But the formula of acid is HaXb,a is the no of H,and b is the no of X.X is an anion is it is in aqueous state.
In this case,KH3(C2H4)2,using the above formula,what does K represents?
(I guess (C2H4)2 is the "X" part.)
Can anyone give some information about this compound?I have googled it but I can't find any information...
Thx a lot.

[Hunter2]

Its Potassium tetroxalate dihydrate.

http://www.chemicalbook.com/ChemicalProductProperty_EN_CB8477350.htm

It is an acidic salt by adding of two molecules of oxalatic acid one half neutralised by potassium.

In water you would have C₂O₄^2- anions.

KH₃(C₂O₄)₂ x 2 H₂O => K⁺ + 3 H⁺ + 2 C₂O₄^2- + 2 H₂O

[Borek]

So is it KH₃(C₂O₄)₂·2H₂O as you put in the thread subject, or KH₃(C₂H₄)₂·2H₂O as you consistently wrote in the question?

H_aX_b is not a general formula of acid. What about sulfuric acid? Or acetic?

[AWK]

Its Potassium tetroxalate dihydrate.

http://www.chemicalbook.com/ChemicalProductProperty_EN_CB8477350.htm

It is an acidic salt by adding of two molecules of oxalatic acid one half neutralised by potassium.

In water you would have C₂O₄^2- anions.

KH₃(C₂O₄)₂ x 2 H₂O => K⁺ + 3 H⁺ + 2 C₂O₄^2- + 2 H₂O

Only traces of C₂O₄^2-

[Hunter2]

Bad soloubility?

[Borek]

No, equilibrium.

[Hunter2]

the equilibrium is on the salt side?

[Borek]

Think about pH of the solution. You have a weak acid.

[davon806]

Thx for all replies.
HaXb means,for example,
H2SO4,a = 2,X = SO4 2-, b =1
CH3COOH, a = 1, X = CH3COO- , b=1
So,I can't substitute the above formula in the case KH3(C2O4)

And consider the equation
KH3(C2O4)2·2H2O + NaOH --> NaH3(C2O4)2 + 2H2O + KOH
so H3(C2O4)2 is an anion with charge 1-?
and the resultant solution is strongly alkaline?
I don't quite understand why neutralization will give out strong alkali(KOH),usually,weak acidic/weak alkaline or neutral salt is given out.

[Hunter2]

I thought you would get sodium- and potassium  oxalate.

[Borek]

KH3(C2O4)2·2H2O + NaOH --> NaH3(C2O4)2 + 2H2O + KOH

No.

so H3(C2O4)2 is an anion with charge 1-?

No.

and the resultant solution is strongly alkaline?

No.

So,I can't substitute the above formula in the case KH3(C2O4)

To some extent you can, you just have to understand what you are looking at.

Have you ever heard about sodium bicarbonate (AKA sodium hydrogen carbonate), NaHCO₃? It is in some aspects quite similar to the compound in question.