theories of acids and bases

what are the two theories of acids and bases?

Arrhenius theory

Bronstead/Lowry theory

what is the Arrhenius theory?

an acid produces hydrogen ions in solution - strong acids (eg HCl) are fully ionised in solution, whereas weak acids (eg ethanoic acid) are only partially ionised in solution

an alkali produces hydroxide ions in solution

neutralisation equation according to Arrhenius theory

H⁺(aq) + OH^- (aq) → H₂O (l)

limitations of Arrhenius theory

only includes reactions in solution (ammonia (g) + hydrochloric acid (g) → ammonium chloride (s) - not in solution

only includes reactions involving hydroxide ions (eg copper oxide + hydrochloric acid → copper chloride + water - no hydroxide ions involved)

Bronstead-Lowry theory

an acid is a proton donor (a H⁺ ion is a proton)

a base is a proton acceptor

general equation for acids added to water

HA(acid) +H₂O → H₃O⁺ + A^-

OFTEN SIMPLIFIED to just a hydrogen ion and A

what is a dative covalent bond

both of the shared electrons come from the same atom

example of a dative covalent bond

reaction of ammonia with hydrochloric acid