2.  Acids are compounds whose characteristic properties include the kinds of reactions they undergo.  Properties: a. tastes sour b. reacts with metals and carbonates c. turns blue litmus paper red.  Common acids are hydrochloric acid, nitric acid, sulfuric acid, carbonic acid, and acetic acid.

3.  Example: tasting a lemon.  Citrus foods like grapefruits and oranges are acidic.  Although sour taste is a characteristic of acids, scientists never taste chemicals in order to identify them.

4.  Acids react with certain metals (magnesium, zinc, iron) to produce hydrogen gas.  This reaction is why acids are described as corrosive.  Corrosive: The way in which acids react with some metals so as to eat away the metal.  Acids are used in a process called etching, Hydrochloric acid eats away metal to form designs.

5.  One product of an acid’s reaction with carbonates is the gas carbon dioxide.  Geologists use this property to identify rocks containing limestone.

6.  Indicator: a compound that changes color when in contact with an acid or a base.  Vinegar, lemon juice, and other acids turn blue litmus paper red.

7.  Base-Another group of compounds that can be identified by their common properties a. Tastes bitter b. Feels slippery c. Turns red litmus paper blue  Opposite of acids  Common Bases are sodium hydroxide, calcium hydroxide, and ammonia.

8.  Although bases are bitter, you wouldn’t want to identify them by doing a taste test.  An example of a base is soap.

9.  A slippery feeling is another characteristic of bases.  Just as you avoid tasting a substance to identify it, you wouldn’t want to touch it.  Strong bases can irritate or burn your skin.

10.  Litmus paper is a safe, reliable test for acids and bases.  Bases turn red litmus paper blue.  An easy way to remember which color litmus turns for acids or bases is to remember the letter b. Bases turn litmus paper blue.

11.  Unlike acids, bases don’t react with carbonates to produce carbon dioxide.  Another important property of bases is how they react with acids.

12.  Manufacturers, farmers, and builders are only some of the people who depend on acids and bases in their work.  Acids are used: a. in food b. to clean brick and metals c. to treat iron and steel d. to make fertilizers  Bases are used: a. To make household cleaning products b. to produce carbon dioxide in baked goods c. to make mortar and cement.