What is the reactant acid in the following reaction

Question

NH3 (aq) + H2O (l) --> NH4+ (aq) + OH- (aq) ?

Answer 1

For most common acid-base reactions, acids may be thought of as the proton (H+) donors, and bases as either the proton acceptors or as the hydroxide (OH-) donors. Water H2O, or H-OH, can act as either an acid or a base. In the reaction with ammonia (NH3) water is donating a proton to form NH4+; that is water is acting as the acid, and ammonia as the base.