16.1 Acid – Ionization

Ionic compounds ionize in water. Strong acids completely ionize, while weak acids only partially ionize. Strong acids brightly light light-bulbs while weak dimly light Hacid(aq) + H2O(l) g Kc =

Kc = Ka Since HAcid is an acid, we can redefine Kc (equilibrium constant) as Ka, the acid-ionization constant. (How much of the acid ionizes).

Ex. 16.1 A 0.012 M soln of HC6H4NO2 has a pH of 3.39. Determine Ka.

Degree of Ionization The DI is the amount of dissociation (x) divided by the initial Molarity. If the % ionization is desired, multiply by 100.

Table 16.1 provides Ka’s for various compounds. Page p 684.

Basic formula: Ka = x2 M-x Three variables to solve for.

A 0. 025 M soln of lactic acid, HC3H5O3 has a pH of 2. 75 A 0.025 M soln of lactic acid, HC3H5O3 has a pH of 2.75. What’s Ka & DI?

Nicotinic acid, HC6H4NO2 has a Ka of 1. 4. 10-5 and a pH of 2. 92 Nicotinic acid, HC6H4NO2 has a Ka of 1.4*10-5 and a pH of 2.92. What’s the molarity of the nicotinic acid? DI?

What are the concentrations of [H+] & [C2H3O2-] in a solution of 0 What are the concentrations of [H+] & [C2H3O2-] in a solution of 0.10 M acetic acid, HC2H3O2? What is the pH? DI? Ka = 1.7*10-5

What is the pH of a 0. 0036M acetylsalicylic acid, HC9H7O4. Ka = 3. 3

Homework: Read 16.1. Complete Q: 23 - 36