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Unformatted text preview: Lecture 11: Acids, Bases, and Salts The Arrhenius Definition (p. 503). A. The Arrhenius definition. 1. An Arrhenius acid is any chemical substance that dissociates in water with liberation of H + ions . Note : A hydronium ion (H 3 O + ) is how we designate a hydrogen ion because the Hydrogen ion does not exist alone but is surrounded by water. 2. An Arrhenius base is any chemical substance that dissociates in water with liberation of OH ions (hydroxide ions) . 3. The Arrhenius definition is used in writing the chemical formula of most common acids and bases. a) An Acid is any electrolytic compound whose chemical formula begins in "H" for the hydrogen ion (H + ). An electrolytic compound is any substance freely giving off ions. b) The subscript of the hydrogen in an acid formula gives the number of hydrogen ions that dissociate in solution. (1) Acids with only one hydrogen ion in their formulas are said to be monoprotic . Hydrochloric acid, HCl is a monoprotic acid. (2) Acids with two hydrogen ions in their formulas are said to be diprotic . Sulfuric acid, H 2 SO 4 is a diprotic acid. (3) And acids with three hydrogen ions in their formulas are said to be triprotic . Phosphoric acid, H 3 PO 4 is a triprotic acid. c) A Base is any electrolytic compound whose chemical formula ends in "OH" for the hydroxide ion (OH ). 4. Properties of acids: a) React with metals to give hydrogen. b) Neutralize bases. c) Taste sour. d) Change blue litmus paper to red. 5. Properties of bases: a) Emulsify fats and oils. b) Neutralize acids. c) Taste bitter. d) Change red litmus paper to blue. Lichens produce a dye called litmus. Lichens are also known as brown alga, a symbiotic relationship between a fungi and alga organisms. Lecture 11: Acids, Bases, and Salts 6. The Arrhenius definition also includes the terms neutralization and salt . a) Neutralization in this sense means the result of mixing an acid with a base and obtaining a neutral solution .....
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