Saturated and Unsaturated Oils and Effect of Temperature on Oil's Viscosity (page 2)

Try New Approaches

1. How are less saturated oils affected by iodine? Repeat the experiment replacing the safflower oil with peanut oil and comparing the results with those of the original experiment (see Figure 6.1). Science Fair Hint: Display colored diagrams to represent the results of the addition of iodine to saturated and unsaturated oils.
2. How does iodine affect the degree of unsaturation of different oils? Repeat the original experiment using different oils, but add the drops of iodine one at a time. Wait until the oil clears before adding the next drop. Continue to add the iodine until the color does not clear. To speed up the process, use a smaller container of oil such as a test tube. Science Fair Hint: Construct and display a bar graph comparing the number of iodine drops added to each sample of oil.

Design Your Own Experiment

1. How do low temperatures affect the way unsaturated bonds are broken? Pour 25 ml of safflower oil into two paper cups. Leave one cup at room temperature and place the second cup in a freezer. After one hour add five drops of tincture of iodine to each cup and stir. Wait five minutes and note any color changes in the cups.
2.  
   1. How does the bonding in an oil affect its freezing point (temperature at which it solidifies)? Fill two small paper cups with oil, one with peanut oil and the other with safflower oil. Label the cup with peanut oil "Saturated" and the cup with soybean oil "Unsaturated." Tilt each cup slowly to determine the viscosity (resistance to flow). Place the cups in a freezer for 2 hours. Remove the cups and test the viscosity again by slowly tilting each cup (see Figure 6.2).
   2. Do the oils return to their original viscosity after warming to room temperature? Allow the cups to sit on a table at room temperature. Test their viscosity by tilting each cup every 10 minutes for one half hour.

Get the Facts

1. Triglycerides are the main compounds in fats and oils. They are made of basic fat molecules. Each contains three molecules of fatty acid and one molecule of glycerol. Use a chemistry text to find out about the formation of triglyceride. What is the structure of glycerine, the building block of triglyceride? What are some of the fatty acids linked to glycerol? Write the reaction between glycerin and carboxylic acid molecules.
2. There is some medical evidence that saturated fats cause deposits to form in blood vessels, thus reducing the blood flow. But not all fats are bad; in fact, we cannot live without some fat in our diet. Information about the amounts and types of fats needed for good health can be obtained from the American Heart Association.
3. In order for fat to be absorbed across the intestinal wall and enter the circulatory system, it must be broken down chemically into smaller molecules. Use a biology text to find out about this emulsification process.
4. The amount of iodine that will combine with fatty acids in fat molecules depends on the number of double bonds the fat molecules contain. Use a nutrition text to find information about the iodine number. You could display a chart listing the common fats and oils and their iodine numbers.

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