Chemistry Are there typos in this snippet causing confusion?

[zenterix]

Homework Statement

I think I have a good understanding of the material I am studying, namely, proton transfer reactions of acids and bases, pH of aqueous solutions, autoprotolysis, buffers, and now acid-base titrations.

Relevant Equations

However, sometimes, there are sections in the book I am reading that seem to contradict what I think I know.

It is rarely clear if there is a typo or if my understanding is incorrect.

Here is an example

Let me go through the concepts here.

The stoichiometric point occurs when the number of moles of acid and base have the same ratio as present in the chemical equation.

In the equation shown above, this is a 1:1 relationship.

Acetic acid is a weak acid and at the stoichiometric point the number of moles of acid present in the analyte has been completely neutralized by exact same number of moles of the titrant sodium hidroxide.

What is left is the salt of the neutralization, which makes the solution basic due to the fact that acetate is the conjugate base of a weak acid.

All fine and good.

And as far as I understand, this is a titration of a weak acid with a strong base.

But then the snippet says that

The converse is true for the stoichiometric point of the titration of any weak acid with strong base.

But didn't we just do a weak acid with a strong base????

The example given is of the titration of aqueous ammonia with HCl.

Now, ammonia in water acts as a base: it accepts a proton to form $\mathrm{NH_4^+}$.

So why is it being considered a weak acid here????

And HCl is a strong acid!

Sure, when all the ammonia is neutralized by the HCl the remaining salt contains a weak acid, ammonium, and so the solution is acid: the stoichiometric point occurs at pH below 7.

So is this confusion due to typos in the snippet or what?

 

[zenterix]

The correct thing seems to be that

In titrations of any weak base with a strong acid, the solution is acid at the stoichiometric point.

In titrations of any weak acid with a strong base, the solution is basic at the stoichiometric point.

 

[Mayhem]

Yes it's a mistake.