Unsaturation of fats (that is, the number of double or triple bonds between carbon atoms) is determined by addition of free iodine (iodine number). Many analytical procedures are based on the release or uptake of iodine and its subsequent titration with sodium thiosulfate (iodometry). Iodine and its compounds are used extensively in analytical chemistry. In the absence of iodine in the water supply, however, goitre and myxedema are prevalent, and a small quantity of iodine in the form of potassium iodide (KI) is frequently added to table salt in order to ensure against iodine deficiency. In many places, drinking water contains sufficient iodine for this purpose. Thyroxine is a hormone that is necessary for maintaining normal metabolism in all the body’s cells. You may be familiar with the chemical symbols for hydrogen and oxygen, but can you match such lower-profile elements as gadolinium and erbium with their corresponding symbols?īecause iodine is converted to thyroxine in the thyroid gland, a small amount of iodine is essential for the body, which contains an average of 14 mg (0.00049 ounce) of the element. Test your bond with the periodic table of elements in this quiz on all 118 chemical elements and their symbols. Several compounds of iodine, such as iodoform (CHI 3), also serve as antiseptics. Iodine is widely used as a disinfectant and antiseptic, frequently in a solution of alcohol and water containing potassium iodide. Another formerly important source of iodine for commercial preparation was the saltpetre or nitrate deposits of Chile, in which iodine is present as solid iodates, especially calcium iodate, Ca(IO 3) 2. Alternatively, addition of cupric sulfate gives cuprous iodide. The final solution, which contains 30–100 grams per litre (4–13 ounces per gallon) of iodine, is treated with sulfuric acid in order to decompose any sulfite, and sulfide and manganese dioxide are added to release iodine, which is vaporized and purified by sublimation.
This is dried and burned the ash is leached with water sodium sulfate and sodium chloride are removed by crystallization and the remaining solution is concentrated by evaporation of water. In an alternate process, chlorine is used as the oxidizing agent:įor a long time, iodine has been recovered on a commercial scale from seaweed. The product is heated with potassium carbonate to give potassium iodide, which is then oxidized to the free element with dichromate and sulfuric acid: The copper iodide that forms is removed by filtration, washed with water, dried, and finely ground. Impurities, such as clay, sand, and oil, are removed by filtration, and the solution is passed through a stream of sulfur dioxide and then through a number of containers holding bundles of copper wire. Natural brines, or brines extracted from oil wells containing up to 150 mg per litre (0.02 ounce per gallon) of iodine, are found in Java, California, and northern Italy the world’s top producers include Chile, Japan, China, Russia, and Azerbaijan. Iodine is produced commercially from iodine-containing brines. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.
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