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The color of chemicals is a physical property of chemicals that in most cases comes from the excitation of electrons due to an absorption of energy performed by the chemical. The study of chemical structure by means of energy absorption and release is generally referred to as spectroscopy .
Several of the CPK colors refer mnemonically to colors of the pure elements or notable compound. For example, hydrogen is a colorless gas, carbon as charcoal, graphite or coke is black, sulfur powder is yellow, chlorine is a greenish gas, bromine is a dark red liquid, iodine in ether is violet, amorphous phosphorus is red, rust is dark orange-red, etc.
Potassium bromide (K Br) is a salt, widely used as an anticonvulsant and a sedative in the late 19th and early 20th centuries, with over-the-counter use extending to 1975 in the US. Its action is due to the bromide ion (sodium bromide is equally effective). Potassium bromide is used as a veterinary drug, in antiepileptic medication for dogs.
A flame test involves introducing a sample of the element or compound to a hot, non-luminous flame and observing the color of the flame that results. [4] The compound can be made into a paste with concentrated hydrochloric acid, as metal halides, being volatile, give better results. [5] Different flames can be tried to verify the accuracy of ...
In chemistry, chromism is a process that induces a change, often reversible, in the colors of compounds.In most cases, chromism is based on a change in the electron states of molecules, especially the π- or d-electron state, so this phenomenon is induced by various external stimuli which can alter the electron density of substances.
A bromate is a chemical compound that contains this ion. Examples of bromates include sodium bromate (NaBrO 3) and potassium bromate (KBrO 3). Bromates are formed many different ways in municipal drinking water. The most common is the reaction of ozone and bromide: Br − + O 3 → BrO − 3
The colour fades at low temperatures so that solid bromine at −195 °C is pale yellow. [31] Liquid bromine is infrared-transparent. [36] Like solid chlorine and iodine, solid bromine crystallises in the orthorhombic crystal system, in a layered arrangement of Br 2 molecules. The Br–Br distance is 227 pm (close to the gaseous Br–Br ...
Should the brown colour not disappear, possibly due to the presence of an alkene which doesn't react, or reacts very slowly with, bromine, the potassium permanganate test should be performed, in order to determine the presence or absence of the alkene. [2] The iodine value is a way to determine the presence of unsaturation quantitatively.