Acid Properties • Donate H + ions The pH Scale • Taste sour • React with certain metals to produce hydrogen gas • React with bases to Is a substance an form salt and water • Most formulas start acid or a base? with H • pH < 7 What is a hydrogen ion?? 1 2 USES OF ACIDS What is an ion? • Citric acid and ascorbic acid (Vitamin C) are found in orange juice • Carbonic acid and phosphoric acid give a An ion is an atom that has “bite” to soft drinks lost or gained an electron • Acids in your stomach aid in digestion • Sulfuric acid is the most widely used giving it a positive (+) or industrial acid in the world. It is used in negative (-) charge. making metals, paper, paints, and fertilizers. 3 4 BASES Small Intestine • A base is any compound that increases the number of hydroxide ions (OH-) • pH 8, slightly when mixed with water basic • i.e, they are H+ acceptors • most chemical • A base solution tastes bitter digestion • A base solution feels slippery completed here k • A base reacts with acids to form salt and water • pH > 7 5 6 1
Detecting Acids Uses of Bases and Bases • Bases are used in soaps • You can detect an acid using an (remember, bases are slippery) indicator. • Bases are used to make paper, in oven cleaners, and to unclog drains • INDICATOR - A substance that • Ammonia is a base and is used in changes color in the presence of an many household cleaners acid or a base. 7 8 Commonly used indicators phenolphthalein • Indicators are substances that colorless in acid change color in solutions of different pink in base pH changes at pH 8.0 -10.0 • Litmus paper is an indicator An acid turns blue litmus paper red A base turns red litmus paper blue • Cabbage juice can be used as an indicator 9 10 Indicator bromothymol blue • A compound that • blue in base changes color when • yellow in acid in contact with an • green in neutral acid or a base. • Bases turn red litmus paper blue. • Acids turn blue litmus paper red. 11 12 2
Which sponge is holding an acid? 13 3
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