Question

does the order in which you mix reagents affect the reaction that occurs?
i.e. does A+B=B+A

I know that the answer to the question is YES but dont know why so please help me.

i reacted equimolar amounts of acid and base and measured the ph after each ml was added.

Answer 1

yes

Answer 2

i know that its yes. i need to know WHY?

Answer 3

sometimes it matters, and sometimes it doesn't. In a reaction like the one you're describing, if you add small amounts of acid to a large amount of base, you'll get a steady decrease in pH. If you add small amounts of base to a large volume of acid, you'll get a steady increase in the pH.

Here, because the volumes added are not equal the order matters. If you were to add equal volumes of equimolar acid and base, the order would not matter.