This document discusses salt hydrolysis, which is the reaction of salt ions with water that can result in an acidic, basic, or neutral solution. Salts formed from a weak acid and strong base produce a basic solution, as the conjugate base of the weak acid will accept protons from water. Salts formed from a weak base and strong acid produce an acidic solution, as the conjugate acid of the weak base will donate protons to water. Salts formed from a strong acid and strong base produce a neutral solution. Examples of sodium ethanoate and ammonium chloride are provided to illustrate basic and acidic salt hydrolysis.

2. 
Salt Hydrolysis: reaction of the anions or
cations in a salt with water to form an
acidic or basic solution.

3. Salt + water = ?
1. Neutral solution
2. Basic solution
3. Acidic solution

4. Salt + water = ?
1. Neutral solution:
Conjugate of strong Acid + conjugate of strong Base  neutral solution
•Things to consider:
–Metal hydroxides of group I and II except Be are strong bases
–All other metal hydroxides are weak bases

5. Salt + water = ?
1. Neutral solution:
2. Basic solution:
Conj. of weak acid + Conj. of strong base  basic solution

6. 
Sodium Ethanoate
(CH3COONa)
› The salt of a weak acid
(CH3COOH) and a strong base
(NaOH)
› Completely ionizes in solution:
CH3COONa  CH3COO- + Na+
› CH3COO- acts as a base
 Will take H+ from water!
CH3COO- + H2O
OH-
CH3COOH +
 Why is the resulting solution
basic?

7. Salt + water = ?
1. Neutral solution:
2. Basic solution:
3. Acidic solution:
Conj. of weak base + Conj. of strong acid  acidic solution

8. 
Ammonium Chloride (NH4Cl)
› NH4Cl is the salt of a strong acid (HCl) and a
weak base (NH3)
› Completely ionizes in solution:
NH4Cl  NH4+ + Cl› NH4+ acts as an acid in water
NH4+ + H2O
H3O+ + NH3
 Why is the resulting solution acidic?

9. 
Determine if the following aqueous
solutions will be acidic, basic or neutral:
› NH4NO3
› KCl
› NaHCO3
› Na2SO3

10. When the negative ion is from a weak
acid then the salt is basic by hydrolysis
 When the positive ion is from a weak
base then the salt is acidic by hydrolysis
 If the salt is formed from a strong acid
and strong base then it is neutral
 If the salt is formed from a weak acid
and weak base then its hydrolysis is
determined by the relative Ka and Kb
values


11. 
This effect is typified in aluminium salts
(the aluminium ion has a charge of 3+)
which are very acidic in solution.