Think, Pair, Share What can you tell me about acids and bases? Can you think of some acids and bases that you might find at home? Are all acids harmful? What foods that we eat or drink are bases? Can you tell the difference by taste?

pH Basics A measure of hydrogen ion concentrations is the pH scale. On the pH scale, high concentrations of hydrogen ion are denoted by low pH and low concentrations of hydrogen ion (high concentrations of hydroxide ion) are denoted by high pH.

pH – “Potential for Hydrogen” Red cabbage extract changes to many colors depending on acidity. Acidity is measured on a pH scale. pH stands for "potential for Hydrogen." Acidity is caused by hydrogen atoms that have lost their electrons and are roaming free in water [H+]. The scale goes from 0 to 14.

More Info on Atoms, Molecules , & Ions http://www.miamisci.org/ph/hoh.html Please go to the website above for more information on atoms, molecules, and ions.

Table 17-2, p. 518

pH Scale The opposite of acidic is alkaline (or basic). Alkaline gets its name from the "al kali" plant whose ashes are capable of neutralizing acids.

Cabbage Juice There are substances which have the property of changing their color when they come in contact with an acidic or basic environment. These substances are called pH indicators. Red cabbage juice is a natural pH indicator.

Cabbage Juice Cabbage juice turns bright pink in the presence of an acid. Cabbage juice turns blue/green/yellow in the presence of a base.

Grape Juice Grape juice turns deep red in the presence of an acid. Grape juice turns blue in the presence of a base. Grape juice is a natural pH indicator.

Acids vs. Bases Acids Taste sour Examples include lemons, vinegar, cola, and green apples. Bases Taste bitter Examples include cleaning solutions like soapy water, detergents, baking soda, and shampoo.

Extra Info for the Test Distilled water is a neutral. High amounts of hydrogen ions mean a low pH value. This is an acid. Low amounts of hydrogen ions mean a high pH value. This is a base. Examples of Acids – lemon juice, orange juice, vinegar, colas, and green apples Examples of Bases – soaps, detergents, baking soda, shampoo, borax, limewater, and ammonia.