What is the role of the phosphoric acid in asprin synthesis? PROVIDE A MECHANISM which expl...

What is the role of the phosphoric acid in asprin synthesis? PROVIDE A MECHANISM which explains the role of this

chemical in this reaction.

---I know that phosphoric acid is needed because it is an acid and as an acid it acts as a catlyst in this experiment. What I do not know is how to provide a mechanism which explains the role of this checmical reaction