Carboxyl Acidic Hydrogens?

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BeylemZ-1B
Posts: 95
Joined: Thu Jul 25, 2019 12:17 am

Carboxyl Acidic Hydrogens?

Postby BeylemZ-1B » Wed Nov 27, 2019 7:13 pm

I understand the rule that any acid with a carboxyl group is considered a weak acid. Why?

For example:
CH3COOH is a weak acid.

AGulati_4A
Posts: 74
Joined: Sat Sep 07, 2019 12:19 am

Re: Carboxyl Acidic Hydrogens?

Postby AGulati_4A » Wed Nov 27, 2019 7:17 pm

Because the intramolecular forces are extremely strong in the molecule. The dipole moment in the molecule most definitely shifts away from the hydrogen which pulls it towards the molecule and thus is harder to separate from it. It is a weak acid if it has a strong bond and vice versa

Veronica_Lubera_2A
Posts: 106
Joined: Sat Sep 14, 2019 12:16 am
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Re: Carboxyl Acidic Hydrogens?

Postby Veronica_Lubera_2A » Wed Nov 27, 2019 9:14 pm

There are significantly more weak acids than strong acids. Weak acids have lower Ka, so larger pKa, meaning they will dissociate more. In class today, he said HI is a strong acid because I is less electronegative and larger, meaning that the bond is longer (weaker) and it will be easier to break. In HF, on the other hand, fluorine has high electronegativity and is smaller, so the bond is shorter (stronger) and will be harder to break; so HF is a weak acid.

For carboxyl groups, I like to think of them as long strands which increase the surface area of a molecule. So when the molecule is added to water, there is a higher chance of the carboxyl tail breaking and reacting with its surroundings.


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