test for unsaturated fatty acid, for my discussion, pliz...?

Question

The test use olive oil, butter, oleic acid, and stearic acid dissolved in ethanol as a sample.. and the, iodine solution in chloroform was added drop by drop into each respective test tube..the ability of the test compunds to decolorized the solution of iodine was observed.

Answer 1

I'm not exactly sure what your question was. But -- unsaturated fatty acids contain cis double bond(s) in the hydrocarbon chain. The reason why iodine would be discolored when unsaturated fatty acids would be added is that iodine (I2) adds to both sides of the double bond. Saturated fatty acids would not add to such effect because saturated fats contain all single bonds (ie the carbons are saturated with hydrogen) and so iodine cannot add or "stick" to the fat.

Basically, olive oil and oleic acid are unsaturated and should have discolored a relatively large amount of the iodine solution (essentially, they "consumed" the iodine when the I molecules added across the double bonds). When the test compounds failed to discolor the iodine solution anymore, the fatty acid double bonds were saturated with iodine.

Butter and stearic acid are both saturated fatty acids and should have failed to discolor the iodine solution fairly quickly (much fewer drops of I2 should have been required).

Answer 2

An unsaturated fatty acid has double bonds someplace in the form, a saturated fatty acid has basically single C-C bonds. look it up on wikipedia, it fairly is a incredibly straightforward answer.