7.3 Describing Acids and Bases Mr. Sapalicio Physical Science Monterey Highlands Elementary

? What do lemons and vinegar have in common? They both taste sour - the acids in lemons and vinegar cause them to taste sour. That is 1 of many characteristics of acids.

Acids & Bases background info You may not know it, but you come in contact with acids and bases when cooking, cleaning, and eating. Have you ever used baking soda in the kitchen? Baking soda is a base. Maybe you have eaten salad dressing with vinegar in it – vinegar is a weak form of acetic acid. Citrus fruits that you eat contain citric acid. If you drink a carbonated soda, carbonic acid is created when the carbon dioxide in the soda combines with water in your body.

More Acid & Base info If you have ever combined vinegar with baking soda, you have seen that a chemical reaction occurs. The fizzing and foaming that results is due to the interaction between the acid (vinegar) and the base (baking soda).

Okay a little more Acid & base info You also have acids and bases in your body. One of the best examples is in your stomach. Human stomachs contain hydrochloric acid that is used to digest food. The stomach acid must be kept away from the rest of the body because it is very harsh and can cause damage. lining of your stomach is specially built to survive the acidic environment.

Types of acids Hydrochloric Acid- digestive, Stomach Nitric Acid- fertilizers, explosives, and rocket fuels Sulfuric acid- fertilizers, paints, detergents, and explosives Carbonic Acid- carbon, soda Acetic Acid- used as a solvent and in the manufacture of rubber, plastics, pharmaceuticals, and photographic chemicals. It is the chief acid of vinegar. Citric Acid- found in fruits.

Properties of Acids Acids- compounds whose characteristic properties include the kinds of reactions they undergo. Acid: A solution that has an excess of H+ ions. It comes from the Latin word “acidus” that means "sharp" or "sour".  An acid tastes sour, reacts with metals and carbonates, and turns blue litmus paper red. Properties of acids include- Sour Taste, Reacts with metals, reacts with carbonates, and turns blue litmus paper red.

Sour Taste Many fruits contain acids The sour taste you experience when you eat them is the citric acid. *But never taste a chemical to determine what type of substance they are.*

Reactions with metals Acids react with certain metals which seem to disappear this is called; Corrosion- the ability to wear away other materials. Acids are considered corrosive because they eat away at metals and other materials.

Reactions with carbonates Carbonate is CO3(2-) and will react with acids to give off carbon dioxide (CO2), leaving the acid salt of the original carbonate salt. acid + metal --> carbon dioxide + water + salt solution

Reactions with indicators Indicator- a compound that changes color when in contact with an acid or base. Litmus paper Acids turn blue litmus paper red Bases turn red litmus paper blue.

Properties of bases Bases are identified by their common properties. Base: A solution that has an excess of OH- ions. Substance that can accept hydrogen ions

Bitter taste Bases taste bitter, you can get the bitter taste from; Citric peels, coffee, unsweetened cocoa, tonic water. Soaps and shampoos as well, but those are *accidental* tastes.

Slippery feel Slippery feel in the shampoo is a characteristic of bases. *do not touch to determine if it is a base or not* Strong bases can irritate the skin or burn it.

Reactions with indicators Bases turn red litmus paper blue. Bases turn litmus paper Blue.

Uses of acids and bases Acids and bases have many uses around the home and industry. P. 272 for some ideas.

Acids and bases

Create a double bubble Acids Bases