The iodine number in chemistry is the mass of iodine in grams that is consumed by 100 grams of a chemical substance. A iodine solution is violet in color and any chemical group in the substance that reacts with iodine will make the color disappear at a precise concentration. The amount of iodine solution thus required to keep the solution violet is a measure of the amount of iodine sensitive reactive groups. Chemistry (in Greek: χημεία) is the science of matter and its interactions with energy and itself (see physics, biology). ... General Name, Symbol, Number iodine, I, 53 Series halogens Group, Period, Block 17 (VIIA), 5, p Density, Hardness 4940 kg/m3, no data Appearance violet-dark grey, lustrous Atomic properties Atomic weight 126. ... A chemical substance is any material substance used in or obtained by a process in chemistry: A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in fixed proportions. ...

One application of the iodine number is the determination of saturation of fatty acids as double bonds in fatty acids also react with iodine compounds. In a typical procedure the acid is treated with an excess of the Hanus solution which is a solution of iodobromine (BrI). Unreacted iodobromine is reacted with potassium iodide which converts it to iodine. The iodine concentration is then determined by titration with sodium thiosulfate. A unsaturated compound in chemistry is a chemical compound that contains carbon - carbon pi bonds such as a alkene or a alkyne. ... In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ... Potassium iodide is a white crystalline salt with chemical formula KI, used in photography and radiation treatment. ... Sodium thiosulfate (Na2S2O3) is a colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3 · 5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposulfite or “hypo. ...

See also

• Saponification value
• Acid number