Hold up! First we need to review!

1. Acids – Arrhenius Definition Produce Hydronium ions (H3O+1) in water Hold up! First we need to review! H +1 -1 +1 H O H water O O H H H H Hydronium ion By this definition, if an acid is to give a H+1 to water, then all acids will have hydrogen as the cation (first element written). Bases – Arrhenius Definition Bases produce the hydroxide ion in water Hydroxide ion

2. 1 7 14 Highly acidic neutral Very basic (not acidic) Ok, here we go… the pH Scale • It is a scale to measure the acidity of a sample. It measures the concentration of hydronium (H3O+1)ions in the solution.

3. pH of Common Substances water (pure) 7.0 vinegar 2.8 soil 5.5 gastric juice 1.6 carbonated beverage 3.0 drinking water 7.2 bread 5.5 1.0 M NaOH (lye) 14.0 blood 7.4 potato 5.8 orange 3.5 1.0 M HCl 0 milk of magnesia 10.5 urine 6.0 apple juice 3.8 detergents 8.0 - 9.0 bile 8.0 lemon juice 2.2 milk 6.4 tomato 4.2 ammonia 11.0 seawater 8.5 bleach 12.0 coffee 5.0 13 11 12 14 1 9 10 0 2 3 4 6 7 5 8 basic neutral acidic [H+] = [OH-] Timberlake, Chemistry 7th Edition, page 335

4. How does the scale work? pH scale : measures acidity/basicity Søren Sorensen (1868 - 1939) ACID BASE 10x 10x 10x 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 NEUTRAL Each step on pH scale represents a factor of 10. pH 5 vs. pH 6(10X more acidic) pH 3 vs. pH 5 (100X different) pH 8 vs. pH 13 (100,000X different)

5. Richter Scale - Earthquakes 6 5 7 . 4 3 2 1

6. radius = 112.8 cm radius = 35.7 cm radius = 11.3 cm radius = 3.6 cm radius = 1.1 cm radius = 0.1128 cm . pH = 2 pH = 3 pH = 1 . pH = 4 5 6

7. Acid pH = 7 [OH-] [H+] = [H+] [OH-] Acidic Basic The pH Scale Base Neutral

8. pH of Common Substance pH [H1+] [OH1-] pOH 14 1 x 10-14 1 x 10-0 0 13 1 x 10-13 1 x 10-1 1 12 1 x 10-12 1 x 10-2 2 11 1 x 10-11 1 x 10-3 3 10 1 x 10-10 1 x 10-4 4 9 1 x 10-9 1 x 10-5 5 8 1 x 10-8 1 x 10-6 6 6 1 x 10-6 1 x 10-8 8 5 1 x 10-5 1 x 10-9 9 4 1 x 10-4 1 x 10-10 10 3 1 x 10-3 1 x 10-11 11 2 1 x 10-2 1 x 10-12 12 1 1 x 10-1 1 x 10-13 13 0 1 x 100 1 x 10-14 14 NaOH, 0.1 M Household bleach Household ammonia Lime water Milk of magnesia Borax Baking soda Egg white, seawater Human blood, tears Milk Saliva Rain Black coffee Banana Tomatoes Wine Cola, vinegar Lemon juice Gastric juice More basic 7 1 x 10-7 1 x 10-7 7 More acidic

9. pH pH = -log [H1+] Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 285

10. Acid – Base Concentrations 10-1 pH = 3 pH = 11 OH- H3O+ pH = 7 10-7 concentration (moles/L) H3O+ OH- OH- H3O+ 10-14 [H3O+]<[OH-] [H3O+]>[OH-] [H3O+]=[OH-] acidic solution neutral solution basic solution Timberlake, Chemistry 7th Edition, page 332

11. pH pH + pOH = 14 pOH pH Calculations [H3O+] pH = -log[H3O+] [H3O+] = 10-pH [H3O+] [OH-] = 1 x10-14 [OH-] pOH = -log[OH-] [OH-] = 10-pOH

12. pH pH + pOH = 14 pOH pH + pOH = 14 This is true because 1 to 14 is the whole range of the scale. Therefore, what ever part is not hydronium ions is composed of hydroxide ions.

13. Auto-ionization of Water [H3O+] • Water will split into ions 2 H2O  H3O+1 + OH-1 • Water will do this to make sure that they come to equilibrium and this is true: [H3O+1] × [OH-1] = 1 × 10-14 • Therefore, if you know the concentration of one you always know the concentration of the other! How handy! [H3O+] [OH-] = 1 x10-14 [OH-]

14. Example Problems !! Example: Find the pH of an acid if the pOH is 12

15. Example Problems !! Example: Find the pH if the concentration of [H3O+1] is 0.25 M Is the pH acidic or basic?

16. Example Problems !! Example: Find the [H3O+1] if the pH is 2.7

17. Example Problems !! Example: Find the [OH-1] if the pH is10.7 ***Keep in mind there is more than one way to go about this***