Oxidation-reduction processes underlie the most important phenomena of animate and inanimate nature: combustion, decomposition of complex substances, synthesis of organic compounds. Potassium permanganate, the properties of which we will study in our article, is one of the most powerful oxidizing agents used in laboratory and industrial conditions. Its oxidizing ability depends on the oxidation state of the atom, which changes during the course of the reaction. Let's consider this on specific examples of chemical processes occurring with the participation of KMnO molecules4.
Characteristic of the substance
The compound we are considering (potassium permanganate) is one of the most widely used substances in industry - manganese compounds. S alt is represented by crystals in the form of regular dark purple prisms. It dissolves well in water and forms a raspberry-colored solution with excellent bactericidal properties.characteristics. Therefore, the substance has found wide application both in medicine and in everyday life as a bactericidal agent. Like other compounds of heptavalent manganese, s alt is capable of oxidizing many compounds of organic and inorganic nature. The decomposition of potassium permanganate is used in chemical laboratories to obtain small volumes of pure oxygen. The compound oxidizes sulfite acid to sulfate. In industry, KMnO4 is used to isolate chlorine gas from hydrochloric acid. It also oxidizes most organic substances and is capable of converting ferrous s alts into its ferric compounds.
Experiments with potassium permanganate
A substance commonly called potassium permanganate decomposes when heated. The reaction products contain free oxygen, manganese dioxide and a new s alt - K2MnO4. In the laboratory, this process is carried out to obtain pure oxygen. The chemical equation for the decomposition of potassium permanganate can be represented as follows:
2KMnO4=K2MnO4 + MnO2 + O2.
Dry matter, which is purple crystals in the form of regular prisms, is heated to a temperature of +200 °C. The manganese cation, which is part of the s alt, has an oxidation state of +7. It decreases in the reaction products to +6 and +4, respectively.
Ethylene oxidation
Gas hydrocarbons belonging to different classesorganic compounds have both single and multiple bonds between carbon atoms in their molecules. How to determine the presence of pi bonds underlying the unsaturated nature of an organic compound? For this, chemical experiments are carried out by passing the test substance (for example, ethene or acetylene) through a purple solution of potassium permanganate. Its discoloration is observed, since the unsaturated bond is destroyed. The ethylene molecule is oxidized and turns from an unsaturated hydrocarbon into a dihydric saturated alcohol - ethylene glycol. This reaction is qualitative for the presence of double or triple bonds.
Features of chemical manifestations of KMnO4
If the oxidation states of the reactants and reaction products change, then an oxidation-reduction reaction occurs. It is based on the phenomenon of movement of electrons from one atom to another. As in the case of the decomposition of potassium permanganate, and in other reactions, the substance exhibits pronounced properties of an oxidizing agent. For example, in an acidified solution of sodium sulfite and potassium permanganate, sodium, potassium and manganese sulfates are formed, as well as water:
5Na2SO3 + 2KMnO4 + 3H2 SO4 =2MnSO4 + 5Na2SO4 + K2SO4 + 3H20.
In this case, the sulfur ion is a reducing agent, and manganese, which is part of the complex anion MnO4-, exhibits the properties of an oxidizing agent. It accepts five electrons, so its oxidation state goes from +7 to +2.
Influence of environment onthe flow of a chemical reaction
Depending on the concentration of hydrogen ions or hydroxyl groups, acidic, alkaline or neutral nature of the solution in which the redox reaction occurs is distinguished. For example, with an excess content of hydrogen cations, a manganese ion with an oxidation state of +7 in potassium permanganate lowers it to +2. In an alkaline environment, at a high concentration of hydroxyl groups, sodium sulfite, interacting with potassium permanganate, is oxidized to sulfate. A manganese ion with an oxidation state of +7 goes into a cation with a charge of +6, which is in the composition of K2MnO4, the solution of which has a green color. In a neutral environment, sodium sulfite and potassium permanganate react with each other, and manganese dioxide precipitates. The oxidation state of the manganese cation decreases from +7 to +4. Sodium sulfate and alkali - sodium hydroxide are also found in the reaction products.
Use of s alts of manganese acid
The reaction of decomposition of potassium permanganate when heated and other redox processes involving s alts of manganese acid are often used in industry. For example, the oxidation of many organic compounds, the release of gaseous chlorine from hydrochloric acid, the conversion of ferrous s alts to trivalent. In agriculture, a solution of KMnO4 is used for pre-sowing treatment of seeds and soil, in medicine they treat the surface of wounds, disinfect inflamed mucous membranes of the nasal cavity,used to disinfect personal hygiene items.
In our article, we not only studied in detail the process of decomposition of potassium permanganate, but also considered its oxidizing properties and applications in everyday life and industry.
