## Chemistry: The Central Science (13th Edition)

According to Arrhenius, an acid is a substance that increases the concentration of $H^+$ ($H_3O^+$) when reacts with water. And according to Bronsted-Lowry definition, an acid is a substance capable of donating a proton $(H^+)$ to another substance.
That difference can be noticed when, for example, $HCl$ react with $NH_3$: $HCl(g) + NH_3(g) --> NH_4Cl (s)$ In this case, HCl is considered a Bronsted-Lowry acid, but not an Arrhenius acid.