Why must we use iodine to identify the fats in oil? What is the chemical explanation and the reaction that happens during the discoloration of...
Iodine or bromine are commonly used to determine the content of unsaturated fats in oil. Unsaturated fats are so called since they contain one or more double bonds. Iodine or bromine attaches to these double bonds and hence a solution of such a halogen gets decolorized. Thus, if we have a given concentration of iodine solution, to which the oil sample is added, the leftover amount of iodine will determine the amount of unsaturated fats in the given sample.
The following is an example reaction for this process:
`CH_3(CH_2)_7CH=CH(CH_2)_7COOH + 3I_2 -> CH_3(CH_2)_7CI_2-CI_2(CH_2)_7COOH + 2HI`
Here, the oleic acid reacts with iodine, which attaches to the carbon atoms at the double bond. This loss of iodine from the solution causes decoloration of the solution. The left over iodine can be measured by titration against sodium thiosulfate.
Hope this helps.
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