Drill: Calculate the pH of 0.10 M H2Z in

0.50 M KHZ.Ka1 = 2.0 x 10-5

Ka2 = 5.0 x 10-9

Salt orHydrolysis Reactions

HydrolysisAny reaction in which water

is decomposed with all or part of its decomposition

portions combining with the products

Hydrolysis

Water is added to decompose something

Hydrolysis

MX + HOH

HX + MOH

Salts

Salts•Ionic compounds

that dissolve ~ 100 % in water

Salts of Acids•Salts of acids are

negative

(A-)

Salts of Bases•Salts of bases are

Positive

(M+ or B+)

Salt Solutions•When salts dissolve,

their ions can recombine with water

Salt Solutions•The salts of weak acids

can recombine with water producing basic

solutions

Salt Solutions•The salts of weak bases can recombine with water producing

acidic solutions

Salt Solutions

A- + H2O HA + OH-

B+ + H2O H+ + BOH

Drill: Calculate the salt/acid ratio of a

solution of benzoic acid & sodium benzoate at a

pH of 5.00.Ka HBz = 6.4 x 10-5

Salt or Hydrolysis Problems

Salt Problem•Calculate the pH of

a 0.20 M solution of NaBz

•Ka HBz = 6.4 x 10-5

Drill: Calculate the pH of a solution of

0.10 M NH3 in 0.20 NH4Cl.

Kb NH3 = 1.8 x 10-5

Salt or Hydrolysis Problems

Salt Problem•Calculate the pH of

a 0.20 M solution of KNO2

•Ka HNO2 = 7.1 x 10-4

Salt Problem•Calculate the pH of a

0.10 M solution of R-NH3Cl

•Kb R-NH2 = 2.5 x 10-5

Calculate the pH of a 0.18 M solution

of KC2H3O2

•Ka = 1.8 x 10-5

Drill: Calculate the salt to acid ratio required to make a buffer solution

with a pH of 4.495 using benzoic acid.Ka HBz = 6.4 x 10-5

Salt Applications

•Salts of strong acids & weak bases make

acidic solutions

Salt Applications

•Salts of strong bases & weak acids make

basic solutions

Salt Applications

•Salts of strong acids & strong bases make

neutral solutions

Predict Relative pH

•NaAc MnCl2

•KNO3 NH4Br

•KHSO4 NH4Ac

Predict Relative pH

•KAc NaCl

•KClO2 NH4Cl

•K2SO4 NaI

Anhydrides•Compounds without

water; that when added to water, form

other compounds

Acid Anhydrides

•Non-metal oxides that form acids when

added to water

Basic Anhydrides

•Metal oxides that form bases when added to water

Predict Relative pH

•Na2O SO2

•NO2 CO2

•CaO Al2O3

Calculate the pH of a 0.16 M solution

of KC7H5O2

•Ka = 6.4 x 10-5

•Calculate the pH of a solution of 0.0030 M KQ.

•Ka HQ = 3.0 x 10-5

Drill: Calculate the pH of a 0.72 M

NH4NO3 solution.Kb NH3 = 1.8 x 10-5

Are there any questions on

previous material?

A/B eq, Buffer & Salt

Hydrolysis Problem

Calculate [H3PO4], [H2PO4-1],

[HPO4-2], [PO4

-3], [K+], [H+], & pH of 1.0 M KH2PO4 in

0.50 M K2HPO4. Ka1 = 7.5 x 10-3

Ka2 = 6.2 x 10-8

Ka3 = 4.2 x 10-13

You need to make a buffer solution with its greatest

buffering capacity at pH ~ 5.4. In general terms,

describe what acid or base you would chose, & how

you would make the buffer.

11.2 g of KOH was added to 2.0 L of 0.075 M

H2CO3. Calculate the molarity of all ions

present in the solution.Ka1 = 4.4 x 10-7

Ka2 = 4.8 x 10-11

Drill: Calculate the pH of

0.10 M HF. Ka HF = 6.5 x 10-4

Test Review

Expect a straight acid/base

problem like the drill

Calculate the pH of 0.10 M HF in

0.20 M KF. Ka HF = 6.5 x 10-4

Calculate the pH of 0.10 M KF.

Ka HF = 6.5 x 10-4

Predict Relative pH

K2O MgO

ClO2 (NH4)2O

SO3 N2O3

Predict Relative pH

•KAc NaCl

•KClO2 NH4Cl

•K2SO4 NaI

Calculate the pH of 5.0 M KCN.

KaHCN= 5.0 x 10-10

Calculate pH of:0.20 M MOH in

0.50 M MCl

Kb = 5.0 x 10-5

Calculate pH of:0.20 M MCl

Kb = 5.0 x 10-5

Drill: Calculate the pH of

0.20 M KQ. Ka HQ = 8.0 x 10-5

Calculate pH of:

•0.20 M HNO2

•Ka = 2.0 x 10-4

Calculate pH of:•3.0 M HZ in

2.0 M KZ•Ka HZ = 3.0 x 10-5

Calculate pH of:

•0.20 M KR

•Ka HR = 2.0 x 10-5

Calculate pH of:

•2.0 M HQ

•Ka = 2.0 x 10-6

Calculate pH of:•0.60 M HZ in

0.90 M KZ•Ka HZ = 3.0 x 10-5

Calculate pH of:

•0.20 M KQ

•Ka HQ = 2.0 x 10-7

1.5 L of 0.25 M Ba(OH)2 was added to 1.0 L of 0.60 M

H2SO3. Calculate [H2SO3], [HSO3

-], [SO3-2], [H+], [OH-],

& pH of the solution.Ka1 = 1.7 x 10-2

Ka2 = 6.0 x 10-8

Review of Acid/Base descriptions and

Acid/Base, Buffer, & Salt Equilibria

Arhenius, Bronsted-Lowry, & Lewis Acids & Bases

Strong Acids

Strong Bases

Acid rxns

Base rxns

A/B Equilibrium Constants

KW, KA, KB, & pH

Calculate pH of:

•0.025 M HNO3

•0.020 M KOH

150 mL of 0.10 M KOH was added to 100.0 mL of 0.10 M H2CO3. Calculate [H2CO3],

[HCO3-], [CO3

-2], [H+], [OH-], & pH of the solution.

Ka1 = 4.4 x 10-7

Ka2 = 4.7 x 10-11

Calculate [H3A], [H2A-1], [HA-2], [A-3], [K+], [H+],

[OH-], & pH of 2.0 M KH2A. Ka1 = 4.0 x 10-3

Ka2 = 5.0 x 10-8

Ka3 = 2.5 x 10-13

The take-home portion of the test is due by

8:15 tomorrow