The objective of this experiment was to identify the reaction of carbohydrates in Benedict’s test, Barfoed’s test and Iodine test. Carbohydrates are essential to living organisms, and the principal role of carbohydrates is the production of energy. Carbohydrates are groups of sugars that contain carbon, oxygen, and hydrogen in a 1:2:1 ratio. Three main units of carbohydrates are monosaccharides, disaccharides, and polysaccharides. Monosaccharides are a single chain of CH2O while disaccharides are two units bonded together through dehydration reaction but they are both considered sugars. Polysaccharides on the other hand are a combination of three or more units of monosaccharides put together. Carbohydrates are formed by the combination of carbon dioxide and water molecules. The carbohydrates contain two specific functional groups in which are the hydroxyl groups and carbonyl groups. In the carbohydrates, if the sugar contains aldehyde group it called reducing sugar and called non-reducing sugar if didn’t have the aldehyde group. The Benedict’s test shows us which sugars are reducing or non-reducing. Benedict's reagent, which contains Cu2+ ions in alkaline solution with sodium citrate added to keep the cupric ions in solution. The alkaline conditions of this test causes isomeric transformation of ketoses to aldoses, resulting in all monosaccharides and most disaccharides reducing the blue Cu2+ ion to cuprous oxide (Cu2O), a brick red-orange precipitate. Examples of reducing sugar are glucose. Examples of non-reducing sugar are sucrose.
Monosaccharide, which is smallest carbohydrates molecules, can be described by the number of carbons in the chain so that a monosaccharide with five carbons in a chain is a pentose and one with six carbons is a hexose. A monsaccharide contains one sugar unit, and has three to seven carbon atoms. Monosaccharides have a hydroxyl group bonded to each carbon