the chemical formula of potassium nitrate is KNO3.

I. Analysis

Potassium nitrate is an inorganic substance, commonly known as saltpeter, and its chemical formula is KNO3. It is a commonly used nitrogen and potassium compound fertilizer with a molar mass of 11.13g/mol and a density of 2.1g/cm3. It is white granular or crystalline powder at room temperature, odorless and toxic, with pungent taste of salt water, weak hygroscopicity, soluble in water, soluble in liquid ammonia and glycerol, slightly soluble in alcohol, and insoluble in ethanol.

II. Redox reaction

Potassium nitrate is a strong oxidant. The black powder reaction ("one nitrate, two sulfur and three charcoal") utilizes the strong oxidation of potassium nitrate. In this reaction, both sulfur and potassium nitrate are oxidants, and a lot of heat will be released during the reaction. The heat will expand the volume of the reaction product gas to more than 1 times larger than the original solid volume, and eventually an explosion will occur.

iii. brief history of development

7% of the world's potassium nitrate is used in agriculture, and Israel and the United States have the largest output, accounting for about three quarters of the world's total, and Chile ranks third. In 1995, the total capacity of potassium nitrate in the world was about 9, ton-years, of which the direct production accounted for about 75%. The existing production capacity of potassium nitrate in China was about 6, ton-years, and the capacity under construction was also 6, ton-years, of which about 8% of potassium nitrate was used in the industrial sector.

Application field:

1. Medical field

Potassium nitrate can be used to treat dentine hypersensitivity in medical field, and it is a good desensitizer. Potassium nitrate is mostly used as a diuretic for animals (pigs, cows and horses). After taking potassium nitrate, some of it enters the blood in the form of potassium ions and nitrate ions.

2. Industrial field

The original use of industrial potassium nitrate is to make black powder, which is a mechanical mixture of potassium nitrate, charcoal and sulfur. Potassium nitrate is an oxidant, charcoal is a combustible agent, and sulfur is a combustible agent, which can make carbon react with potassium nitrate only to generate carbon dioxide, hinder the generation of carbon monoxide and improve the ignition performance of black powder.

3. Agriculture

Potassium (K) and nitrogen (N) in potassium nitrate are very important crop nutrients. Potassium can improve the intensity of photosynthesis and enhance the disease resistance of plants. Nitrogen is involved in plant hormone synthesis, leaf area expansion and carbon and nitrogen metabolism of crops. Lack of nitrogen or insufficient supply will lead to crop leaves, which will lead to the decrease of crop yield and quality.