Bronsted - Lowry

[hendra81]

my question is;

some references state that when NaOH accept proton (H⁺) became Na⁺ and H₂O and Na⁺ considered as conjugated acid but some other references state that H₂O as conjugated base.

please answer my question

[liambob1]

The acid is defined as the molecule or ion that is able to donate a proton, and it follows that if the proton is donated that there has to be a species that accepts the election which is called the base. So now have a look at your reaction and see which gains and which looses a proton.

 

acid + base conjugate base + conjugate acid.

Edited March 7, 2011 by liambob1

[Horza2002]

Specifficaly this refers to a Bronsted acid (there are other tyoes of acids e.g. Lewis acids). A Bronstead acid is defined as a species that donates a proton while a Bronstead base is a species that accepts a proton.

 

But remember, once you have deprotonated your acid, it will become negatively charged and will therefore want to take a proton of somewhere (i.e. it is now behaving as a base). For example:

 

HCl^- + H₂O <==> Cl^- + H₃O⁺

Bronstead acid; Bronstead base; Conjugate base; Conjugate acid

 

Here, the HCl is acting as a baseacid...but once it have reacted with the water, the chloride ion left will them want to act as a base to move the equilibrium backwards. Essentially, the roles are reveresed.

Edited March 7, 2011 by Horza2002

[hendra81]

thanks 4 the answer.

i'm asking this because i've confuse about some references state that Na ion (in CH3COONa) cannot be hydrolyzed because Na ion is a weak caonjgated acid

[Horza2002]

I would explain that observation in a different manor. I would say that water is not a strong enough acid to protonate the carboxylate (i.e. the carboxylate is more stable than the resulting hydroxide ion would be).