CHEM L110 - Chemistry and Society Laboratory
INTRODUCTION
Chemistry is the study of matter and the changes that matter undergoes. These changes are chemical reactions. Our lives as well as our quality of life are dependent on many different types of chemical reactions. Chemical reactions are used to produce or store energy. Chemical reactions are used in analytical procedures. Chemical reactions are used to synthesize materials, both those already known and those yet to be discovered.
In this experiment you will synthesize two compounds. The first compound is an ester. Esters belong to a class of organic compounds that are used as flavorings or fragrances. The second compound is a polymer. Polymers are large molecules formed by the bonding together of many smaller molecules. Common plastics are made from polymers.
EXPERIMENTAL PROCEDURE
-------------- Ester Synthesis --------------
You will be instructed to do either Procedure #1 or #2.
Procedure #1: Methyl Salicylate
Use a large dry test tube. Place 3 mL of methanol in the test tube. Carefully note the odor of the methanol. In the methanol, dissolve (with stirring) ~0.5 g of salicylic acid. Now carefully note the odor of the mixture. After all of the salicylic acid is completely dissolved, slowly and carefully add 10 drops of concentrated sulfuric acid (H2SO4). Do not remove the bottle of concentrated H2SO4 from the fume hood. Stir the solution and then place the test tube in a hot water bath for at least 10 minutes. Stir the solution frequently during this 10 minute period. After 10 minutes, slowly and carefully pour the contents of the test tube into a small beaker containing ~20 mL of hot water. Carefully note the odor of the ester. Try to identify the odor.
Procedure #2 Pentyl Acetate
Use a large dry test tube. Place 3 mL of pentanol in the test tube. Carefully note the odor of the pentanol. To the
pentanol, add (with stirring) 1 mL of acetic
acid. Now carefully note the odor of the mixture. Slowly
and carefully add 10 drops of concentrated sulfuric acid (H2SO4).
Do not remove the bottle of concentrated H2SO4 from the fume hood.
Stir the solution and then place the test tube in a hot water bath
for at least 10 minutes. Stir the solution frequently during this 10
minute period. After 10 minutes, slowly and carefully
pour the contents of the test tube into a small beaker containing ~20 mL of hot water.
Carefully note the odor of the ester. Try to identify the odor.
-------------- Polymer Synthesis
--------------
Pour 20 mL of poly(vinylalcohol) solution into a plastic cup. Add one drop of your favorite food color (two or more drops if you are going to mix colors). Stir. Add 4 mL of borax solution to the poly(vinylalcohol) mixture and stir vigorously with your white spatula. Observe what happens. You can handle the new polymer that you just made. Observe its physical properties.
