ACIDS & BASES

Acids are compounds which taste sour. Some common acids are:

1. acetylsalicylic acid--aspirin

2. ascorbic acid--vitamin C

3. carbonic acid--in carbonated beverages such as Coca Cola

4. citric acid--in fruits such as oranges, grapes, lemons and grapefruit

5. lactic acid--an acid which causes muscles to fatigue. Lactic acid is also found in milk.

6. acetic acid--vinegar is 5% acetic acid and 95% water

7. oxalic acid--combines with calcium to form kidney stones, and is used to clear radiators. Oxalic acid is found in many green leafy vegetables and in tea.

8. hydrochloric acid--stomach acid

9. sulfuric acid--the acid used in automobile batteries

10. carbolic acid--also known as Phenol. Phenol was the first antiseptic. It was developed by Joseph Lister, and made aseptic surgery possible.

11. Malic acid-acid found in apples

Strong acids:

1. sulfuric acid

2. nitric acid

3. hydrochloric acid

4. acetic acid

Weak acids:

1. carbonic acid

2. phosphoric acid

3. citric acid

4. oxalic acid

All matter is composed of atoms. Atoms have a nucleus which contains particles called protons and neutrons. Protons have a positive electrical charge, and neutrons are neutral. Orbiting the nucleus of an atom are electrons. Electrons have a negative electrical charge. In all atoms except for hydrogen, the numbers of protons, neutrons and electrons are equal to each other. Hydrogen has one proton and one electron, but no neutron. Because atoms have protons and electrons in equal number, atoms are electrically neutral. If an atom should lose or gain and electron, it becomes an electrically charged ion.

Electrons orbit the nucleus in shells or energy levels. The lowest energy level is the level

closest to the nucleus. Higher energy levels move away from the nucleus. The first energy level requires two electrons to be full. The second requires eight to be full. All atoms want to have an outer energy level which is full. Therefore, atoms will react with other atoms to achieve a full outer shell.

Sometimes atoms will share electrons with other atoms to achieve a more complete outer shell. This is the covalent chemical bond. Sometimes atoms will steal electrons and become oppositely charged ions. Since opposite electrical charges attract, the ions are attracted into the ionic chemical bond.

How acids are formed: Hydrogen has one proton, no neutron and one electron. It wants to gain a second electron to fill its only energy level. If, however, its electron is stolen by another atom, hydrogen becomes a free (naked) proton. A free proton is an acid. It wants to have two electrons in it energy level, so it is very reactive. Acids are corrosive because they try to tear electrons away from anything in an attempt to gain the electrons that they want.

Hydrochloric acid forms when hydrogen and chlorine are placed in water. Hydrogen has one electron. Chlorine has seven valence electrons. When placed in water the chlorine steals the hydrogen's electron and becomes the chloride ion (Cl-). When the chlorine steals the hydrogen's electron, the hydrogen becomes a free (naked) proton (hydrogen ion H+). The hydrogen ion tears away at everything to try to gain the electrons that it wants. This action makes the acid corrosive. The free proton joins with a water molecule to form H30. So the acid (free proton) exists as H3O.

The class of compounds which are the opposite of acids are called bases. Bases are sometimes referred as being alkaline. If a substance is only slightly basic, it is called an alkaloid. All bases are slippery and taste bitter. Examples of bases are:

1. sodium hydroxide or lye--used to clear metal plumbing pipe.

2. ammonia--used to clean many things

How bases are formed: To illustrate how bases are formed, Sodium hydroxide (NaOH) will be used as an example. When NaOH is placed in water, it ionizes into Na+ OH-. Sodium (Na) has only one valence electron. The OH steals this electron making the Na positive and the OH negative. The OH- ion is called the hydroxyl ion. This

stolen electron in the OH- ion is wanted by other forms of matter, and they attack the OH- to steal this electron. This attacking action makes bases caustic.

Definitions:

1. caustic--capable of converting some types of animal and vegetable matter into soluble materials by chemical action. This means that it can burn tissue. Bases are caustic.

2. corrosive--to eat away or destroy by chemical action. This means that it destroys by breaking up.Acids are corrosive.

All acids produce the hydrogen ion (H+) when placed in water. All bases produce the hydroxyl ion (OH-) when placed in water.

(H+) log= the log of hydrogen ion concentration. p is the sign for negative log. This was put together and shortened to pH. So pH is the negative log of hydrogen ion concentration. The pH scale runs from 0--14. pH 0is a 100% H+ ion concentration--a very strong acid. A pH of 7 occurs when the H+ concentration equals the OH- ion

concentration.

Because a pH of 7 is an equal H+, OH- concentration any substance with a pH of 7 is neutral. Any substance with a pH above 7 has a higher concentration of OH- ions, and is basic.

Being a logarithmic scale, an increase in pH of one is equal to ten times the alkalinity or acidity. An acid with a pH of 3 is ten times stronger than an acid with a pH of 4.

Common pH:

1. sulfuric acid= pH 2

2. hydrochloric acid= pH 2

3. milk= pH 7.4

4. sodium hydroxide (lye, Draino)= pH 13-14

5. milk of magnesia= pH 11

6. pure water= pH 7

Acidity is tested with litmus paper. Bases turn red litmus paper from red to blue. Acids turn blue litmus paper from blue to red. Phenolphthalein is colorless in an acid, but turns pink in a basic solution. Therefore, phenolphthalein is a base indicator. Phenolphthalein is the ingredient in X-Lax laxative. Acids and bases are use to dissolve things. The digestive system used hydrochloric acid to dissolve protein in the stomach. The small intestines use bile, a base, to dissolve fats. Bile is made in the liver from worn out red blood cells. When it is not needed it is stored in the gall bladder to be released when needed again. This is why people who have had their gall bladder removed are

advised to avoid excesses of fatty foods.