Home > Community > Why does the pH fall during hydrolysis?
Upvote

12

Downvote
+ Chemistry
+ Organic chemistry
+ Hydrolysis
Posted by
Ahmed Moawed

Why does the pH fall during hydrolysis?

Andrew Wrigley  Follow

Why does the pH fall during hydrolysis?

You need to specify what kind of compound is being hydrolyzed.

If you are discussing esters, then

RC(=O)—OR’ + H[math]_2[/math]O → RC(=O)OH + R’OH

The reactants, ester and water, are neutral. The products are a carboxylic acid (which will of course be … an acid) and an alcohol, which is neutral.

And it’s easy to see why the pH will fall. We’re producing a solution with more overall acidic substances in it.

But if we detour to discussing amides, then

RC(=O)—NR’R” + H[math]_2[/math]O → RC(=O)OH + R’R”NH

The reactants are, again, both neutral. The products are a carboxylic acid and an amine: an acid and a base. And, depending on the values of the pKa of the acid and the pKb of the base, it’s entirely possible for the pH of this reaction mixture to rise during hydrolysis.

More

Upvote

VOTE

Downvote