I am doing an experiment using iodine and different types of oils. The longer it takes for the iodine to discolour, is it more SATURATED or UNSATURATED?This is the procedure: 1. Label the test tube...

I am doing an experiment using iodine and different types of oils. The longer it takes for the iodine to discolour, is it more SATURATED or UNSATURATED?

This is the procedure:

1. Label the test tube based on the type of oil.
2. Measure 5cc of the cooking oil using the measuring cylinder.
3. Place it in the proper test tube.
4. Using the eyedropper, drip one drop of iodine into each oil.
5. Immediately start the stop watch and record the time taken for the dark color of
iodine to turn clear.
6. Repeat steps 2-5 for the other cooking oils.

So the longer it takes for the iodine to discolour, is the more SATURATED OR UNSATURATED?
 
I've searched on the net and some say SATURATED, others say UNSATURED. I'm really confused. Please help!

Asked on by limobean

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Top Answer

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ncchemist | eNotes Employee

Posted on

The terms saturated and unsaturated refer to the presence or absence of carbon carbon double bonds in the fatty acid chains of the various oils.  Oils that have no double bonds (all single bonds only) are called saturated since the fatty acid chains are saturated, or maximized, with hydrogen.  Oils that have double bonds present are unsaturated.  Iodine (I2) readily reacts with the double bonds in fatty acids.  When iodine is added to an unsaturated oil, the dark color will disappear as the iodine reacts with the double bonds.  When iodine is added to a saturated oil, the dark color never disappears since there is nothing for the iodine to react with.  The speed with which the color disappears is based on how many double bonds are present in that particular oil.  The more double bonds there are, the faster the iodine will react and the color disappear.  So the longer it takes for the color to disappear, the more saturated the oil is.

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