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Acids, Bases, and pH

Acids, Bases, and pH. Glencoe: Chapter 24 Sections 3 and 4 Pages 764-774. I. What are acids?. Substances that donate hydrogen ions, H + , to form hydronium ions, H 3 O + , when dissolved in water. 1+. Formation of Hydronium Ions. 1+. 1+. +. H +. H 2 O. H 3 O +. hydrogen ion. water.

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Acids, Bases, and pH

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  1. Acids, Bases, and pH Glencoe: Chapter 24 Sections 3 and 4 Pages 764-774

  2. I. What are acids? • Substances that donate hydrogen ions, H+, to form hydronium ions, H3O+, when dissolved in water

  3. 1+ Formation of Hydronium Ions 1+ 1+ + H+ H2O H3O+ hydrogen ion water hydronium ion (a proton)

  4. A. Characteristics of acids 1. Acids turn blue litmus paper red  Litmus paper is an indicator 2. Acids taste sour 3. Can burn skin

  5. Common Acids Battery acid Sulfuric Acid H2SO4 Nitric Acid HNO3 Phosphoric Acid H3PO4 Hydrochloric Acid HCl Acetic Acid CH3COOH Carbonic Acid H2CO3 Used to make fertilizers and explosives Food flavoring Stomach acid Vinegar Carbonated water

  6. B. Strong vs. Weak acids 1. Strong acids – ionize (break in to cations and anions) almost completely, and conduct electricity well a. Nitric acid (HNO3) b. Hydrochloric acid (HCl) c. Sulfuric acid (H2SO4) d. Perchloric acid

  7. B. Strong vs. Weak acids 2. Weak acids – do not completely ionize a. Acetic acid (vinegar) b. Citric acid c. ALL others

  8. II. What are bases? - Substances that form hydroxide ions (OH-) ions when in water, or accept H+ ions

  9. A. Characteristics of Bases 1. Taste bitter 2. Slippery 3. Bases turn red litmus paper blue 4. Can burn skin

  10. B. Strong vs. Weak bases 1. Strong bases - ionize (break into cations and anions) almost completely, and conduct electricity well a. KOH – potassium hydroxide b. NaOH – sodium hydroxide 2. Weak bases - do not completely ionize a. Ammonia (NH3)

  11. Review • Acid: A solution that has an excess of H+ ions. It comes from the Latin word acidus that means "sharp" or "sour". • Base: A solution that has an excess of OH- ions. Another word for base is alkali. • Aqueous: A solution that is mainly water. Think about the word aquarium. AQUA means water.

  12. III. Why is a substance neutral? • A substance is neutral when: 1. It does not ionize at all, therefore no H+ or OH- ions 2. It has equal concentrations (amounts) of H+ and OH- ions

  13. IV. How acidic or basic is it? A. pH – measures the concentration of H3O+ ions  Crowded Not Crowded   More crowded = More concentrated  Critical to certain processes and functions - example: enzymes, blood B. pH  indicates H3O+ and OH- concentrations

  14. Concentration vs. Strength • Concentration is not the same as strength • Concentration deals with the amount of hydronium ions in the solution, compared to the amount of water in the solution.  More acid or base and less water = more concentrated  More ions and less molecules = stronger

  15. III. How acidic or basic is it? C. pH scale  0-14  Indicates concentration of hydronium ions 0-6 = acid  closer to 0 is more acidic 8-14 = base  closer to 14 is more basic 7 = neutral  H3O+ concentration = OH- concentrations

  16. III. How acidic or basic is it? D. Each pH unit = a power of ten - Example: pH 3 is 100 times more acidic than pH 5

  17. Review • Strong Acid: An acid that has a very low pH (0-4). • Strong Base: A base that has a very high pH (10-14). • Weak Acid: An acid that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (3-6). • Weak Base: A base that only partially ionizes in an aqueous solution. That means not every molecule breaks apart. They usually have a pH close to 7 (8-10). • Neutral: A solution that has a pH of 7. It is neither acidic nor basic.

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