Acids & Bases - Chemistry

Acids & Bases 24Bronsted-Lowry Definition of a Acid: a substancethat donates a H + .Consider the reaction of a weak base with water:NH 3 (aq) + H 2 ONH 4 + (aq) + OH − (aq)Because this is an equilibrium, NH 4+ (aq) donates a H + (aq)that reacts with OH − (aq) to produce the original NH 3 (andwater). Therefore, NH 4+ (aq) is acting like an acid! Since itstarted as a weak base (NH 3 ), we call NH 4+ a conjugate acid.Strong bases have weak conjugate acids.Weak bases have stronger conjugate acids.In the two reactions shown on this page and the previous,water is acting as either an acid or a base. Any chemical thatcan act as either an acid or base is called amphoteric.In the following reaction, Na + is more accurately calleda conjugate Lewis Acid (not a proton donor).NaOH(aq)Na + (aq) + OH − (aq)