Question regarding Di/Triprotic Acids

[stester77s]

Hello,

Take concentrated H2SO4.

There are two reactions at play:

Reaction 1: H2SO4 ---> H+ + HSO4-
Reaction 2: HSO4- ---> H+ + SO4(2-)


Does Reaction 2 not begin until reaction 1 goes all the way to completion? For example, in very concentrated H2SO4 (99% to 1% water), reaction 1 will not go to completion: so does reaction 2 not even move at all? Does this mean that the SO4 (2-) concentration is effectively zero?

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[syoung]

You could probably figure it out based on pKa, and concentrations.

also http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch17/diprotic.php

 

[Teleologist]

Does Reaction 2 not begin until reaction 1 goes all the way to completion? For example, in very concentrated H2SO4 (99% to 1% water), reaction 1 will not go to completion: so does reaction 2 not even move at all? Does this mean that the SO4 (2-) concentration is effectively zero?

You're mixing a kinetics question with a thermo question. I'm not entirely sure about the answer to your kinetics question (i.e. when the reactions start happening).

The answer to your second question is that in a very concentrated solution of sulfuric acid, yes, the sulfate ion concentration is rather low.

Regarding the ionization extent of sulfuric acid solutions, here's a post I made yesterday about sulfuric acid. Hope it helps: