4.5 Acid-Base Equilibria

strong acid def

A strong acid is fully dissociated into its ions/in solution,

HCI ￫ H+ + Cl-

H2SO4 ￫ 2H+ + SO42-

HNO3 ￫ H+ + NO3-

Weak acid def

weak acid is partially dissociated into its ions in solution,

CH3COOH = H+ CH3COO-

HNO2 = H+ + NO2-

strong base Def

strong base is fully dissociated into its ions in solution,

NaOH ￫ Na+ + OH-

KOH ￫ K+ + OH-

weak base Def

weak base is partially dissociated in its ions in solution

NH3 + H2O = NH4+ + OH-

Conjugate pairs answer

amphoteric Examples

H2O, H2PO4-, HCO32-

pH equation

pH = - log10[H+]

H+ equation

[н+] = 10-рн

Ka equation

Ka meaning

Acid dissociation constant

pKa equation

pKa = - log10 [Ka]

Pka to Ka equation

Ka = 10 -pka

Kw meaning

Ionic product of water

Kw equation

Kw = [H+][OH-]

Strong alkali Kc equation

Units of Kw

mol2dm-6

• Explain why expression for Kw does not contain H2O

• [H20] is very high compared to [H+] and [OH-]

• -H2O only dissociates - slightly equilibrium lies to the LHS

• [H2O] is effectively constant

[H+] for strong alkali equation

Brønsted-Lowry acid Def

proton donor

Brønsted-Lowry base

proton acceptor

Monobasic acids Def

donate one proton per molecule of acid; eg. HCl, CH3COOH

Dibasic acids Def

donate two protons per molecule acid; eg. H2SO4.