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The reagent is an alkaline solution of potassium permanganate. Reaction with double or triple bonds (R 2 C=CR 2 or R−C≡C−R) causes the color to fade from purplish-pink to brown. Aldehydes and formic acid (and formates) also give a positive test. [43] The test is antiquated. Baeyer's reagent reaction
Potassium permanganate will decompose into potassium manganate, manganese dioxide and oxygen gas: 2 KMnO 4 → K 2 MnO 4 + MnO 2 + O 2 This reaction is a laboratory method to prepare oxygen, but produces samples of potassium manganate contaminated with MnO 2 .
A permanganate (/ p ər ˈ m æ ŋ ɡ ə n eɪ t, p ɜːr-/) [1] is a chemical compound with the manganate(VII) ion, MnO − 4, the conjugate base of permanganic acid.Because the manganese atom has a +7 oxidation state, the permanganate(VII) ion is a strong oxidising agent.
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]
Potassium permanganate is an oxidizing agent. [5] The British National Formulary recommends that each 100 mg be dissolved in a liter of water before use. [3] Potassium permanganate was first made in the 1600s and came into common medical use at least as early as the 1800s. [6] It is on the World Health Organization's List of Essential Medicines ...
Potassium dichromate is an oxidising agent in organic chemistry, and is milder than potassium permanganate. It is used to oxidize alcohols. It converts primary alcohols into aldehydes and, under more forcing conditions, into carboxylic acids. In contrast, potassium permanganate tends to give carboxylic acids as the sole products.
Depending on the conditions in which the titration is performed, the manganese is reduced from an oxidation of +7 to +2, +4, or +6. In most cases, permanganometry is performed in a very acidic solution in which the following electrochemical reaction occurs: [3]
Manganates are unstable towards disproportionation in all but the most alkaline of aqueous solutions. [2] The ultimate products are permanganate and manganese dioxide , but the kinetics are complex and the mechanism may involve protonated and/or manganese(V) species.