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It is a purplish-black crystalline salt, which dissolves in water as K + and MnO − 4 ions to give an intensely pink to purple solution. Potassium permanganate is widely used in the chemical industry and laboratories as a strong oxidizing agent , and also as a medication for dermatitis , for cleaning wounds , and general disinfection .
The chemical chameleon reaction shows the process in reverse, by reducing violet potassium permanganate first to green potassium manganate and eventually to brown manganese dioxide: [1] [2] [5] KMnO 4 (violet) → K 2 MnO 4 (green) → MnO 2 (brown/yellow suspension) Blue potassium hypomanganate may also form as an intermediate. [6]
This reaction illustrates the relatively rare role of hydroxide as a reducing agent. The concentration of K 2 MnO 4 in such solutions can be checked by measuring their absorbance at 610 nm. The one-electron reduction of permanganate to manganate can also be effected using iodide as the reducing agent: 2 KMnO 4 + 2 KI → 2 K 2 MnO 4 + I 2
The white smoke-like vapor produced by the reaction is a mixture of carbon dioxide gas and water vapor. Since the reaction is highly exothermic, initial sparking occurs, followed by a lilac- or pink-colored flame. [9] When energy or heat is added to electrons, their energy level increases to an excited state.
Water-reactive substances [1] are those that spontaneously undergo a chemical reaction with water, often noted as generating flammable gas. [2] Some are highly reducing in nature. [ 3 ] Notable examples include alkali metals , lithium through caesium , and alkaline earth metals , magnesium through barium .
Heterogeneous OER is sensitive to the surface which the reaction takes place and is also affected by the pH of the solution. The general mechanism for acidic and alkaline solutions is shown below. Under acidic conditions water binds to the surface with the irreversible removal of one electron and one proton to form a platinum hydroxide. [4]
The first solvation shell of a sodium ion dissolved in water. An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, also known as sodium chloride (NaCl), in water would be represented as Na + (aq) + Cl ...
Potassium metal can react violently with water producing KOH and hydrogen gas. 2 K(s) + 2 H 2 O(l) → 2 KOH(aq) + H 2 (g)↑ A reaction of potassium metal with water. Hydrogen is produced, and with potassium vapor, burns with a pink or lilac flame. Strongly alkaline potassium hydroxide is formed in solution.