There are many reference substances for the calibration of potassium permanganate, including Na?C?O?, H?C?O?.2H?O, As?O?, (NH?)?SO?, FeSO?.6H?O, and pure iron wire. Among them, Na?C2O? is most commonly used because it contains no water of crystallization, has no hygroscopicity, is heat-stable, and is easy to refine.

In H?SO?solution, MnO?- reacts with C2O?- as follows:

2MnO?- + 5C2O?- + 16H+ = 2Mn?+ + 10CO? + 8H?O

Since this reaction is very slow at room temperature, the solution should be heated to 75-85 degrees Celsius, but the temperature should not be too high or it will cause partial decomposition of C?O?- and skew the results.

When the temperature is greater than 90 degrees Celsius, C2O?- decomposition reaction is as follows:

2H+ + C2O?- = CO? + CO + H?O

Potassium permanganate is one of the strongest oxidizing agents, as an oxidizing agent is greatly affected by the pH, the oxidizing ability is the strongest in acidic solutions, as a strong oxidizing agent, it can be decomposed automatically to generate heat and cause combustion by contact with organic matter. The oxidizing ability is the strongest in acidic solution.

Expanded Information:

Potassium permanganate is a strong oxidizing agent, and is often used as an oxidizing agent in laboratories and industry. As an oxidizing agent, it is decomposed when it meets ethanol. In the acidic medium will slowly decompose into manganese dioxide, potassium salt and oxygen. Light has a catalytic effect on this decomposition, so it is often stored in a brown bottle in the laboratory.

From the graphs of elemental potentials and oxidation states of free energies, it can be seen that it is extremely oxidizing. In alkaline solutions, its oxidizing properties are not as strong as in acidic ones. When used as an oxidizing agent its reduction products vary according to the acidity or alkalinity of the medium.

In the production of chemicals, widely used as oxidizing agent, such as used in the production of saccharin, vitamin C, isoniazid and benzoic acid oxidizing agent; medicine used as antiseptic, disinfectant, deodorant and antidote; in the purification of water and wastewater treatment, as a water treatment agent, in order to oxidize hydrogen sulfide, phenol, iron, manganese, and organic, inorganic and other pollutants, odor control and decolorization. It is also used as bleaching agent, adsorbent, coloring agent and disinfectant.

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