[Wil"]

Why does some reactions have to be conducted in acidic/basic medium??

Is it because to enable the reactants be completely oxidized/reduced??

eg 5Br-(aq) + BrO3-(aq) + 6H+(aq) → 3Br2(aq) + 3H2O(l)

Is my assumption correct??

the acid doesn't act like a catalyst,right? then do we have a name for its function??

[Borek]

the acid doesn't act like a catalyst,right? then do we have a name for its function??

Yes, it is called reactant.

Its presence ensures high redox potential of the system and reduces risk of side reactions consuming other reactants.