Show Labelled Diagram of iodine is burning in breaker on burner
Answers
Testing for carbohydrates
Testing for the presence of starch (complex sugar)
Lugol's reagent (iodine solution) changes from yellowish-brown to dark purple/black.
Testing for simple carbohydrates (monosaccharides and some disaccharides)
Benedict's solution is used to test for simple carbohydrates. Benedict's solution is a blue colored liquid that contains copper ions. When Benedict's solution and simple carbohydrates are heated, the solution changes to orange red/ brick red. This reaction is caused by the reducing property of simple carbohydrates. The copper (II) ions in the Benedict's solution are reduced to Copper (I) ions, which causes the color change. Sometimes a brick red solid, copper oxide, precipitates out of the solution and collects at the bottom of the test tube. Complex carbohydrates such as starches DO NOT react positive with the Benedict's test unless they are broken down through heating or digestion (try chewing crackers and then doing the test). Table sugar (disaccharide) is a non-reducing sugar and does also not react with the iodine or with the Benedict Reagent. Sugar needs to be decomposed into its components glucose and fructose then the glucose test would be positive but the starch test would still be negative.