Question

Explain why the titration of a strong acid with a strong base stays at a low pH value until very near to the stoichiometric point.

I understand why the pH for a strong acid/strong base titration must equal 7 at the stoichiometric point, but I don't really understand the reasoning behind the shape of the titration curve and why it stays low until very near the stoichiometric point.

Answer 1

A strong acid dissociates very easily

And when we add a strong base to the solution slowly

Some of the acid reacts with added base to form salt and the pH of solution increases

But due to the strength of the acid the pH rises very slowly despite the strong base addition

For strong acid even a small concentration is able to maintain low pH

But at equivalence point where all the acid is consumed the dramatic change is observed

I hope this helps if you have any query or want more detailed explanation feel free to ask in the comments section below.