# Hydrogen Ions and Acidity

## Presentation on theme: "Hydrogen Ions and Acidity"— Presentation transcript:

Hydrogen Ions and Acidity
Chapter 19.2

What is Kw? Kw is the equilibrium constant for the self-ionization of water Water molecules are in constant motion and can collide to create a hydronium ion and a hydroxide ion

Where does Kw come from? 2H2O(l)  H3O+(aq) + OH-(aq) Kw = [H+][OH-] __________ [H2O]2 But we remove liquids and solids Kw = [H+][OH-]

Self Ionization Concentration Ion-Product Constant
Called the self-ionization of water [H+] = [OH-] = 1.0 x 10-7 M The ion-product constant for water (Kw) Kw = [H+][OH-] = 1.0 x M2 Neutral solution [H+]=[OH-] Acidic solution [H+] > [OH-] Basic solution [H+] < [OH-]

pH Scale and Formulas pH is an easier way to express the strengths of acids and bases pH scale ranges from 0-14 0-6 considered acidic RED 7 considered neutral 8-14 considered basic BLUE pH = -log [H+] [H+] = antilog(pH) pOH = -log [OH-] [OH-] = antilog(pOH) pH + pOH = [H+][OH-] = 1.0 x 10-14

Practice Problems What is the pH of a substance that has an [H+] concentration of 1 x 10-4? What about 1 x 10-5? What is the pH of a substance that has an [H+] concentration of x 10-5? 4.0; 5.0; 4.2

Practice Problems What is the [H+] concentration of a substance that has a pH of 8.00? What is the [OH-] concentration? What is the [H+] concentration of a substance that has a pH of 8.73? What is the [OH-] concentration? What is the pOH? 1 x 10-8;1 x 10-6;1.86 x 10-9;5.39 x 10-6; 5.27

Similar presentations