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Theory of acids and bases Chemistry of aq solution - Coggle Diagram
Theory of acids and bases
Chemistry of aq solution
Theory of acids and bases
Arrhenius
Arrhenius acid(produces H+ in an aqueous solution)
Arrhenius base(produces OH- in an aqueous solution)
Limitation: Only apply for aqueous reactions
Brønsted-Lowry
Brønsted-Lowry acid(proton H+ donor)
Brønsted-Lowry base(proton H+ acceptor)
Conjugate acid-base pair(example:NH3 and NH4+)
Limitation:There are reactions with no transfer of proton
Lewis
Lewis acid(electron acceptor)
Lewis base(electron donor)
Current form of acid-base understanding
Chemistry of aq solution
Acid-base equilibrium constant
Kb=[BH+(aq)][OH-(aq)]/[B(aq)]
Increases with strength of basse
Ka=[H3O+(aq)][A-(aq)]/[HA(aq)]
Increases with strength of acid
Ionic product of water Kw=Kc[H2O(l)]
Ka x Kb = Kw
(used to find Ka or Kb of conjugate acid or base)
pKa + pKb = 14 at 25°C only
pKa + pKb <14 above 25°C
Buffer
weak base and its salt
Acidic buffer pH<7
pH=pKa + lg [salt]/[acid]
weak acid and its salt
Alkaline buffer pH>7
pOH=pKb+lg[salt]/[base]
Salt hydrolysis
Acidic salt(weak base strong conjugate acid)
Basic salt(weak acid strong conjugate base)
Finding pH
1.Find the ion that hydrolyse
2.Write hydrolysis equation
3.Find Ka or Kb
4.Find pH using equation and Ka/Kb
Solubility equilibria(Ksp)
[AX+]^Y [BY-}^X
Where X and Y is the charge of the ion
Unit:mol^(X+Y) dm^-3(X+Y)
Constant if temperature constant
Varies only with temperature
Solubility(S)
Unit:Usually g dm-3 or mole dm-3
Maximum amount that can dissolve in a given volume of a particular solvent to give a saturated solution at a specific temperature
Ksp= (YS)^Y (XS)^X
Where X and Y is the charge of the ions
example:AgCl
Ksp=(1S)^1 (1S)^1 = S^2
example:PbCl2
Ksp=(2S)^2 (1S)^1 = 4S^3
Common ion effect
le chatelier's principle
when one of the ion formed is added, position of equilibrium shifts left and the solubility is decreased
Solubility decreases