Acids & Bases (year13)

Proton DONORS • HNO3 • H2SO4 • CH3COOH • HCl

Proton ACCEPTORS • NH3 • NaOH • CH3NH2 • MgO

Bronsted-Lowry ACID~ a proton, H+, donor Bronsted-Lowry BASE ~ a proton, H+ acceptor

• Each acid molecule releases ONE proton into solution HCl(aq) —– H+(aq) + Cl-(aq)

• Each acid molecule releases TWO protons Takes place is 2 stages: • 1st proton released goes to completion • 2nd proton is reversibly released H2SO4(aq): H2SO4(aq) — H+(aq) + HSO4-(aq) HSO4-(aq) (reversible sign) H+(aq) + SO42-(aq) Overall equation: H2SO4(aq) —– 2H+(aq) + SO42-(aq)

• Each acid molecule releases THREE protons Takes place in THREE stages ~ each proton is REVERSIBLY released Phosphoric acid: H3PO4(aq) (reversible sign) H+(aq) + H2PO4-(aq) H2PO4-(aq) (reversible sign) H+(aq) + HPO42-(aq) HPO42-(aq) (reversible sign) H+(aq) + PO43-(aq) Overall equation: H3PO4(aq) — 3H+(aq) + PO43-(aq)

• aqueous acid is NEUTRALISED to form water • state symbols are included in FULL and IONIC equations IONIC EQUATIONS: • ions dissociate in solution, but a solid ionic compound is not • aqueous covalent compounds are NOT split up • spectator ions are cancelled out

• dissociates when the covalent bond breaks • proton is released • Water molecule accepts a proton by forming a DATIVE covalent bond • The hydronium ion, H3O+(aq) is formed

A pair of species which TRANSFORM into each other by the GAIN or LOSS of a PROTON • The difference of a H+ ion links an acid with it conjugate base HNO2(aq) (reversible sign) H+(aq) + NO2-(aq)

HNO2(l) + H2O(l) (reversible sign) H3O+(aq) + NO2-(aq) H2O ~ base competes for proton using O lone pair NO2- ~ base competes for proton using N lone pair Position of acid-base equilibrium is dictated by: • STRENGTH of the two bases • Stability of the anions