Drill: Calculate the pH of 0.10 M H 2 Z in 0.50 M KHZ.

K a1 K a2 = 2.0 x 10 -5 = 5.0 x 10 -9

Salt or Hydrolysis Reactions

Hydrolysis Any 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 + H 2 O HA + OH B + + H 2 O H + + BOH

Drill: Calculate the salt/acid ratio of a solution of benzoic acid & sodium benzoate at a K pH of 5.00.

a HBz = 6.4 x 10 -5

Salt or Hydrolysis Problems

Salt Problem •Calculate the pH of a 0.20 M solution of NaBz •K a HBz = 6.4 x 10 -5

Drill: Calculate the pH of a solution of 0.10 M NH 3 NH 4 Cl.

in 0.20 K b NH 3 = 1.8 x 10 -5

Salt or Hydrolysis Problems

Salt Problem •Calculate the pH of a 0.20 M solution of KNO 2 •K a HNO 2 = 7.1 x 10 -4

Salt Problem •Calculate the pH of a 0.10 M solution of R-NH 3 Cl •K b R-NH 2 = 2.5 x 10 -5

Calculate the pH of a 0.18 M solution of KC 2 H 3 O 2 •K a = 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.

K a 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 •KNO 3 •KHSO 4 MnCl 2 NH 4 Br NH 4 Ac

Predict Relative pH •KAc •KClO 2 •K 2 SO 4 NaCl NH 4 Cl 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 •Na 2 O •NO 2 •CaO SO CO Al 2 2 2 O 3

Calculate the pH of a 0.16 M solution of KC 7 H 5 O 2 •K a = 6.4 x 10 -5

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

•K a HQ = 3.0 x 10 -5

Drill: Calculate the pH of a 0.72 M NH 4 NO 3 K b NH3 solution.

= 1.8 x 10 -5

Are there any questions on previous material?

A/B eq, Buffer & Salt Hydrolysis Problem

Calculate [H 3 PO 4 ], [H 2 PO 4 -1 ], [HPO 4 -2 ], [PO 4 -3 ], [K + ], [H + ], & pH of 1.0 M KH 2 PO 4 in 0.50 M K 2 HPO 4 . K a1 = 7.5 x 10 -3 K a2 = 6.2 x 10 -8 K a3 = 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 H 2 CO 3 . Calculate the molarity of all ions present in the solution.

K a1 K a2 = 4.4 x 10 -7 = 4.8 x 10 -11

Drill: Calculate the pH of K 0.10 M HF. a 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 K 0.20 M KF. a HF = 6.5 x 10 -4

Calculate the pH K of 0.10 M KF. a HF = 6.5 x 10 -4

Predict Relative pH K 2 O ClO 2 SO 3 MgO (NH 4 ) 2 O N 2 O 3

Predict Relative pH •KAc •KClO 2 •K 2 SO 4 NaCl NH 4 Cl NaI

Calculate the pH of 5.0 M KCN. K aHCN = 5.0 x 10 -10

Calculate pH of: 0.20 M MOH in 0.50 M MCl K b = 5.0 x 10 -5

Calculate pH of: 0.20 M MCl K b = 5.0 x 10 -5

Drill: Calculate the pH of K 0.20 M KQ. a HQ = 8.0 x 10 -5

Calculate pH of: •0.20 M HNO 2 •K a = 2.0 x 10 -4

Calculate pH of: •3.0 M HZ in 2.0 M KZ •K a HZ = 3.0 x 10 -5

Calculate pH of: •0.20 M KR •K a HR = 2.0 x 10 -5

Calculate pH of: •2.0 M HQ •K a = 2.0 x 10 -6

Calculate pH of: •0.60 M HZ in 0.90 M KZ •K a HZ = 3.0 x 10 -5

Calculate pH of: •0.20 M KQ •K a 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 H 2 SO 3 . Calculate [H 2 SO 3 ], [HSO 3 ], [SO 3 -2 ], [H + ], [OH ], & pH of the solution.

K K a1 a2 = 1.7 x 10 -2 = 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 K W , K A , K B , & pH

Calculate pH of: •0.025 M HNO 3 •0.020 M KOH

150 mL of 0.10 M KOH was added to 100.0 mL of 0.10 M H 2 CO 3 . Calculate [H 2 CO 3 ], [HCO 3 ], [CO 3 -2 ], [H + ], [OH ], & pH of the solution.

K a1 K a2 = 4.4 x 10 -7 = 4.7 x 10 -11

Calculate [H 3 A], [H 2 A -1 ], [HA -2 ], [A -3 ], [K + ], [H + ], [OH ], & pH of K 2.0 M KH 2 A. a1 = 4.0 x 10 -3 K a2 = 5.0 x 10 -8 K a3 = 2.5 x 10 -13

The take-home portion of the test is due by 8:15 tomorrow