Transcript Chapter 21 Notes, part II Salt Hydrolysis Buffer Solutions Salt Hydrolysis •Remember, Acid+BaseaSalt+Water •Some salts are neutral, but others are acidic or basic. •Why? Because some.

Chapter 21 Notes, part II
Salt Hydrolysis
Buffer Solutions
Salt Hydrolysis
•Remember, Acid+BaseaSalt+Water
•Some salts are neutral, but others
are acidic or basic.
•Why? Because some salts promote
hydrolysis.
•Hydrolysis—the reaction of an ion
with water
Salt Hydrolysis
•The cations or anions from the
dissociated (dissolved in water) salt
remove hydrogen ions from or donate
hydrogen ions to water.
•Depending on the direction of the
hydrogen ion transfer, the salt can
be acidic or basic.
• Strong Acid+Strong BaseaNeutral Solution
• Strong Acid + Weak Base aAcidic Solution
• Strong Base + Weak Acid a Basic Solution
•Why is this?
Are the following salts going to
be acidic, basic or neutral?
NaCl
NH4NO3
KC2H3O2
Ca(ClO3)2
FeBr2
KMnO4
MgSO4
LiNO3
ZnCl2
AgBr
Buffers
•Buffer—A solution in which the pH
remains relatively constant when a
small amount of acid or base is
added.
•A buffer is made by making a
solution of a weak acid and its salt or
a weak base and its salt.
How does a buffer work?
• EX: HC2H3O2 and NaC2H3O2
• In soln, the following reactions take place
HC2H3O2 D H+ + C2H3O2NaC2H3O2 a Na+ + C2H3O2• If acid is added, the acetate ion acts like
a H+ sponge. C2H3O2- + H+ D HC2H3O2
• If a base is added, the acetic acid will
neutralize it! HC2H3O2+OH-DC2H3O2-+H2O
Buffer Capacity
•The buffer capacity is the amount of
acid or base that a buffer can hold
before significant change in pH
occurs.