Titrating Polyfunctional Acids and Bases

1. Treating Complex Acid-Base Systems

• Complex systems are defined as solutions made up of:

(1) An acid or base that has two or more acidic protons or basic functional groups

H3PO4

Ca(OH)2

(2) Two acids or bases of different strengths

HCl + CH3COOH

NaOH + CH3COO-

3) An amphiprotic substance that is capable of acting as both acid and base

HCO3- + H2O <=> CO3

2- + H3O+

HCO3- + H2O <=> H2CO3 + OH-

NH3+CH2COO- + H2O <=> NH2CH2COO- + H3O+

NH3+CH2COO- + H2O <=> NH3+CH2COOH + OH-

Problems

1. Understanding Ka1>Ka2>Ka3…

2. The relationship between Ka and Kb of its conjugate base.

Example 13-1, 2, 3

1. Calculate the hydronium ion concentration of 0.100M NaHCO3 solution.

2. Calculate the hydronium ion concentration of 1.00×10-3M Na2HPO4 solution.

3. Find the hydronium ion concentration of 0.0100M NaH2PO4 solution.

Mixtures of Strong and Weak Acids

Mixtures of Strong and Weak bases?

Problem(P325, 13-25): Identify by letter the curve you would expect in the titration of a solution containing(a) disodium maleate, Na2M, with standard acid (1.3x10-2, 5.9x10-7) (b) pyruvic acid, HP, with standard base (3.2x10-3)(c) sodium carbonate, Na2CO3, with standard acid (1.5x10-4, 4.69x10-11)