Molybdenum disulfide

Molybdenum disulfide is the main component of molybdenite. It is a black solid powder with metallic luster. The chemical formula MoS2 has a melting point of 1185 ° C, a density of 4.80 g / cm3 (14 ° C), and a Mohs hardness of 1.0 to 1.5. It decomposes at the beginning of 1370 ° C and decomposes into metallic molybdenum and sulfur at 1600 ° C. When heated at 315 ° C in the air, it is oxidized at the beginning, the temperature increases, and the oxidation reaction accelerates. Molybdenum disulfide is insoluble in water, dilute acid and concentrated sulfuric acid, and generally insoluble in other acids, alkalis and organic solvents, but soluble in aqua regia and boiling concentrated sulfuric acid. Slow oxidation occurs at 400 ° C to form molybdenum trioxide:

2MoS2 + 7 O2 → 2 MoO3 + 4 SO2 can use titanium iron reagent to check the generated molybdenum trioxide. The product is first treated with sodium hydroxide or potassium hydroxide solution (the principle is to convert molybdenum trioxide to molybdate), and then the titanium reagent solution is added dropwise, which will react with the generated sodium molybdate or potassium molybdate to produce gold. Yellow solution. This method is sensitive and trace amounts of molybdate can be detected. And if it is said that no molybdenum trioxide is formed, the solution will not produce golden yellow, because molybdenum disulfide does not respond well to sodium hydroxide or potassium hydroxide solutions.

Molybdenum disulfide can react with chlorine to generate molybdenum pentachloride. Its chemical equation is:

2 MoS2 + 7 Cl2 → 2 MoCl5 + 2 S2Cl2

Molybdenum disulfide and alkyl lithium react under control to form an embedded compound (interlayer compound) LixMoS2. If it reacts with butyl lithium, then the product is LiMoS2.

Molybdenum disulfide has a high content of active sulfur and is liable to cause corrosion of copper. It is discussed in many books and papers on lubricant additives. In addition, when the parts made of copper and its alloys need to be lubricated, it is not impossible to choose a lubricating product containing molybdenum disulfide, but it is also necessary to add a copper corrosion inhibitor.