EXPERIMENT 33

Some Common Alcohols

MATERIALS. Ethyl alcohol, methyl (wood) alcohol, litmus paper, camphor gum, iodine, a solution of iodine in potassium iodide, sodium hydroxide, patent medicine, ether, olive oil, carbolic acid, glycerin.

APPARATUS. Stirring rod, evaporating dish, test tubes.

A. Properties of the Common Alcohols.

1. What is the chemical name for common alcohol? Write its formula. What is the chemical name for wood

alcohol? Write its formula.

2. Obtain 10 cc. of each liquid in two clean, dry test tubes. Note the odor of each. Describe the difference.

3. Using a clean stirring rod, taste a drop of each. Describe the difference.

Caution: Do not swallow the liquids— they are poisons. Methyl alcohol (wood alcohol) produces blindness and death. Ethyl alcohol is a "habit" producing drug, and produces death ultimately from slow poisoning.

4. Test the solubility of each alcohol in water.

5. Test them with strips of red and with blue litmus. Do alcohols affect litmus?

6. Pour 2 cc. of each alcohol in different evaporating dishes. Apply the flame to each until it burns. Note the color of the flame and the heat given off by each. Do alcohols make good fuels? Which is the most often used for fuel? Why? Why? Could they be used for illuminating purposes? Why? Write the equation to show the products formed when the alcohols burn.

7. To a test tube half filled with water add a piece of camphor gum the size of a bean. Does it dissolve? Pour off

the water and add 5 cc. of ethyl alcohol; shake. Does it dissolve? This forms the so-called "spirits of camphor." Add water to a crystal of iodine. Does it dissolve? Pour off the water and add 5 cc. of alcohol. Result? This is called "tincture of iodine." What are its uses? Is alcohol a good solvent? Why are flavoring "extracts" largely alcohol? Why is it used in patent medicines? Should methyl alcohol be used for these purposes? Why? Ethyl alcohol is used to disinfect wounds. Should methyl alcohol be used for this purpose? Why? Ethyl alcohol is used for "alcohol rubs." Should methyl alcohol be used as well? Why? Why is methyl alcohol used for preserving fruits and vegetables in specimen jars rather than ethyl alcohol?

8. Summarize the properties of the common alcohols. 9. Summarize the uses of each.

10. What is the commercial source of each?

B. Iodoform Test for Ethyl Alcohol (Grain Alcohol).

1. Alcohol can often be detected by its odor or its taste. A better test is the following: To 10 cc. of liquid add 5 cc. of a solution of iodine in potassium iodide. Now add a solution of sodium hydroxide one drop at a time, shaking the mixture well, till the iodine color vanishes. Warm gently, and let it stand for a few minutes. A yellow precipitate of iodoform with its characteristic odor will be formed. If only a small amount of alcohol is present, the crystals may not form but the odor will be recognized.

Try this test upon a solution of 2 cc. of alcohol in 10 cc. of water.

Test a patent medicine for alcohol.

C. Ordinary Ether (C2H5)2O.

Ether is formed by the action of concentrated sulfuric acid upon ethyl alcohol. It is called, for this reason, “sulfuric ether" or "ethyl ether."

1. Obtain 5 cc. of ether. Note its odor. Place a drop on your hand. Is it volatile?

2. Dip the stirring rod into it and hold it in the flame? Is ether inflammable?

3. Dissolve a drop of olive oil in the ether. Is it a good solvent? Why then is it not more often used for cleaning purposes?

4. What is the important use of ether?

D. Phenol or Carbolic Acid, C6H5OH.

1. Pure phenol is a white crystalline substance. Examine a bottle of it, but do not remove any from the bottle.

It is soluble in water. The solution is usually pink due to slight decomposition, and is called carbolic acid.

2. Obtain 1 cc. of carbolic acid in a test tube. Describe its odor. Test it with red and with blue litmus. Is it a true alcohol? Do not get any on the hands; it causes serious burns. Alcohol is the antidote. What is carbolic acid used for?

E. Glycerin, C3H5(OH)3.

1. Obtain 5 cc. of glycerin in a test tube. Has it an odor? Taste it. Result? Pour about 1 cc. into another test tube half full of water. Shake. Is it soluble?

2. Test the solution with litmus. Is it a true alcohol? 3. What is nitroglycerin? What is dynamite? What are they used for?

What important uses has glycerin in the home?

ORGANIC ACIDS

An organic acid is composed of carbon, hydrogen, and oxygen. They all contain one or more carboxyl groups, COOH. They are nearly all crystalline solids. Some acids, such as acetic, tartaric, citric, and oxalic, have a sour taste and affect litmus as inorganic acids do. Others such as stearic, palmitic, benzoic, tannic, and salicylic acids are almost tasteless. As has been noted, these acids react with the alcohols (the organic bases) to form esters (organic salts). These esters are the basis of many of our artificial flavoring extracts and perfumes.

EXPERIMENT 34

Properties and Uses of Some Common Organic Acids MATERIALS. Acetic acid, alcohol, amyl alcohol, concentrated sulfuric acid, vinegar, tartaric acid, sodium bicarbonate, cream of tartar, citric acid, oxalic acid, potassium permanganate solution, tannic acid, ferrous sulfate.

APPARATUS. Test tubes.

A. Acetic Acid, H(C2H3O2) or CH3COOH.

1. Note the odor of a dilute solution of acetic acid. Very carefully taste it. Test it with litmus paper. Result?

2. To 3 cc. of acetic acid add 3 cc. of ordinary alcohol, then, carefully, 3 cc. of concentrated sulfuric acid. Warm and note the sweet odor of ethyl acetate. This is a test for acetic acid. Write the equation and name each substance. CH3COOC2H5+H2O

C2H5OH+CH3COOH

Ethyl acetate is an organic salt formed from an organic acid and an alcohol. These salts are called esters. have sweet odors and are often used for artificial flavorings.

They

To 3 cc. of acetic acid add 3 cc. of amyl alcohol and then 3 cc. of concentrated sulfuric acid. Warm gently and note the odor of the ester amyl acetate. For what artificial flavoring is it used?

3. Obtain 3 cc. of vinegar. Smell it, taste it, and test it with litmus paper. What acid do you think is present? To prove your answer add alcohol and sulfuric acid as in (2) and obtain the ester test. What acid is in vinegar? For what purposes is vinegar used in cooking?

B. Tartaric Acid, H2(C,H,O。) or C2H4O2(COOH)2.

1. Obtain a crystal of tartaric acid. Describe its taste. Pulverize the crystal and dissolve a small portion in water. Test the solution with litmus. Has tartaric acid the characteristic property of an acid?

Mix the rest of the powdered crystal with an equal amount of dry sodium bicarbonate. Is there any action? Now add water. What is given off? Write the equation and name each substance.

NaHCO3+H2C4HО ̧H →→ HNаCHO+H2O+CO2 ·

·

6

Tartaric acid is used in baking powders. Why? (See Experiment 29 on Carbonates.)

2. Cream of tartar is a salt of tartaric acid HKC4H406 (hydrogen potassium tartrate). Taste it. Dissolve a small amount in water and test with litmus. Result? Mix a small amount with sodium bicarbonate. Is there any action? Now add water. Result? Write the equation and name each substance.

HKC,H4O6+NaHCO3- NaKC4H4O6+H2O+CO2