Acid-Base Equilibria Review: In pure water & all aqueous solutions: H2O + H2O = H3O+ + OH-

Solutions of Strong Acids/ Bases: 0.10 M HNO3 actually consists of 0.10 M H3O+ or [H3O+] = 0.10 M 0.10 M NaOH…. Adds 0.10 OH- to the water solution

Solutions of Weak acids/bases 0.10 M HC2H3O2 : a weak acid- when it reacts with water it does not ionize 100%. What is the [H3O+] for this solution? Ka = 1.8 x 10-5

Weak acids (continue) [H3O+] [C2H3O2-] Ka = = 1.8 x 10-5 [HC2H3O2]

Weak acids (continue) So…. 2 = 1.8 x 10-5

Weak bases…. B + H2O = BH+ + OH- NH3 + H2O =

Weak bases (continue) If the [OH-] = 2.5 x 10 -3 , what is the [H3O+]?

pH A simple scale for ranking the H3O+ concentrations of dilute acid/base solutions. (Sorenson). The logarithm of a number is that number expressed as an exponent of the base 10. For example, the logarithm of 1 is 0, 1 x 100.

pH Scale [H3O+][OH-]= 1x10-14 pH = - log[H3O] pH + pOH = 14 Formulas to remember

More About the pH Scale Given a 3.25 x 10-4 M HNO3 , solve for: [H3O+] [OH-]

Sample Problem 1.8 x 10-5 What is the pH of a 0.10 M HC2H3O2 solution? = 1.8 x 10-5 Ka = [HC2H3O2 ]