Acid/Base Equilibrium

Arrhenius’ Theory of Acids & Bases Up until this point, you have learnt Arrhenius’ Theory: An acid dissociates in water to produce H+(aq) E.g. HCl(aq)  H+(aq) + Cl-(aq) A base dissociates in water to produce OH-(aq) E.g. NaOH(s)  Na+(aq) + OH-(aq) However, this theory could not explain exceptions like why NH3 (ammonia) and NaHCO3 (baking soda) were considered bases

Bronsted-Lowry Theory of Acids & Bases An acid is a substance which produces protons (H+), a proton donor A base is a substance which accepts protons, a proton acceptor Two molecules/ions that are related by the transfer of a proton are called a conjugate acid-base pair base conjugate acid H+ acid conjugate base

Conjugate Pairs Example Identify the conjugate acid/base pairs and show the proton transfer acid conjugate base H+ base conjugate acid

Conjugate Pairs Example Identify the conjugate acid/base pairs and show the proton transfer. What is interesting about these systems? base conjugate acid H+ acid conjugate base acid conjugate base H+ base conjugate acid Amphiprotic species can act as either an acid or a base. Has both an H-atom and a lone pair of electrons

Strong Acids and Bases Dissociate completely Quantitative reaction, no dynamic equilibrium Strong Acids Strong Bases All oxides & hydroxides of Group 1 & 2 metals except Be

Weak Acids and Bases Do not dissociate completely Dynamic equilibrium

Practice! Worksheet P. 532 #1,2