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Hydrolysis

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					                                        Hydrolysis

What is hydrolysis?                            A metathesis reaction of a salt with water
                                               to form molecular species (“the reverse of
                                               neutralization,” however salts that undergo
                                               hydrolysis usually are not neutral)
Salt + HOH                                     acid + base (hydrolysis deals with the
                                               formation of a weak acid and/or a weak
                                               base)
Salts of a strong acid and a weak base will    Hydrolyze to give an acidic solution
always…
Salts of a weak acid and a strong base will    Hydrolyze to give a basic solution
always…
Salts of a strong acid and salts of a strong   Never undergo hydrolysis (the resulting
base will…                                     solution is always neutral)
Salts of a weak acid and salts of a weak       Hydrolyze as an acidic, basic, of neutral
base may…                                      solution (depends on the Ka and Kb of the
                                               acids and bases formed during hydrolysis)
If the weak acid formed in hydrolysis is       The overall solution will be slightly acidic
stronger than the weak base formed…
If the weak base formed in hydrolysis is       The overall solution will be slightly
stronger than the weak acid formed…            alkaline/ basic
If the weak acid and base formed during        The overall solution will be neutral
hydrolysis are of equal strength…
Aqueous ammonium chloride undergoes            NH4+ + Cl- + HOH  H+ + Cl- + NH4OH
hydrolysis when placed in water
Aqueous potassium fluoride undergoes           K+ + F- + HOH  K+ + OH- + HF
hydrolysis when placed in water
Sodium chloride and water are mixed            Na+ + Cl- + HOH  Na+ + OH- + H+ + Cl-
together
Ammonium fluoride and water are mixed          NH4+ + F- + HOH  HF + NH4OH
together
The formation of the following products        Ammonium hydroxide, carbonic acid,
through a hydrolysis reaction results in       sulfurous acid
such small concentrations that the product
does not decompose in water or form a gas

				
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