citric/acetic acids (1 Viewer)

[dead]

this question was in the '04 neap paper:
Citric acid and acetic acid are both weak acids. State why citric acid is stronger than acetic acid.

is it something to do with the bonds?.....coz it cant be coz of dissociation....help plz

 

[richz]

it is about dissociation. Citric molecules ionise into more H+ than acetic

 

[dead]

never knew that, so its just a fact that citric ionises more than acetic?

 

[Ednaw]

not certain but i think it just relates to the amount of h+ ions citric donates is more than acetic. I think its possible to work it out from their formulas

Citric C6H8O7 - obviously more than 1

Acetics C2H4O2 - i know it only donates 1 H+

 

[Dreamerish*~]

Citric acid is triprotic. This means it produces 3 H⁺ ions in solution, whereas acetic acid is monoprotic and produces only one.

Both citric and acetic acids are weak acids because they do not ionise completely in solution, while strong acids do. Of course, a weak acid that is monoprotic would still be weaker than a weak acid that is triprotic.

 

[dead]

oh ok that helps alot. i almost forgot totally about mono-, di-, and triprotic acids....hehe

but how do you know whether an acid is triprotic or mono?

 

[Dreamerish*~]

oh ok that helps alot. i almost forgot totally about mono-, di-, and triprotic acids....hehe

but how do you know whether an acid is triprotic or mono?

You can tell with acids such as H₂SO₄, H₃PO₄ and HCl because there are numbers after the H.

With citric acid, it's just something I've always remembered.

 

[jetfan]

Does is relate to the structure of the citric acid molecule??

CH2-COOH
|
CH-COOH
|
CH2-COOH

Can each of these donate the H off the end, reacting with the water to make hydronium ions??

Just a thought

Edit: Make sure you check the number of H's in my diagram, only 2 on corner and one in the middle

 

[Dreamerish*~]

Does is relate to the structure of the citric acid molecule??

CH3-COOH
|
CH2-COOH
|
CH3-COOH

Can each of these donate the H off the end, reacting with the water to make hydronium ions??

Just a thought

Yes, that's right.