brnsted-lowry
We can also consider the reverse reaction in the above equation. In that reaction, the ammonium ion donates a proton to the hydroxide ion. The ammonium ion is a Brnsted-Lowry acid, while the hydroxide ion is a Brnsted-Lowry base. Most Brnsted-Lowry acid-base reactions can be analyzed in this way. There is one acid and one base as reactants, and one acid and one base as products.