Is NH₃ a Arrhenius base? I don't know whether a Arrhenius base requires a OH^- in the molecule.

Kind of but not really, it depends how you look at the reaction. Read this link, it gives a good explanation of the limitations using your example.

 

Truth be told, the Arrhenius definition is inherently limited in its application. Generally we consider amines as acting as either a Lewis base, since amines can donate a lone pair of electrons, or as a Bronsted-Lowry base (which is more or less the same as the Arrhenius definition, but not as limited), as they can accept H^+.

Kind of but not really, it depends how you look at the reaction. Read this link, it gives a good explanation of the limitations using your example.

 

Truth be told, the Arrhenius definition is inherently limited in its application. Generally we consider amines as acting as either a Lewis base, since amines can donate a lone pair of electrons, or as a Bronsted-Lowry base (which is more or less the same as the Arrhenius definition, but not as limited), as they can accept H^+.

 

The page states :

 

"Nevertheless, there are hydroxide ions there, and we can squeeze this into the Arrhenius theory."

so I think it is Arrhenius base

I wouldn't worry too much. The Bronstead and Lewis definitions are much more broad and useful anyway. The Arrenhius definition is by far the most narrow of the commonly used acid/base theories.