Exemplar

Sodium molybdate dihydrate is a chemical compound used in various applications, including as a fertilizer, corrosion inhibitor, and in the synthesis of other chemicals. It's a white, crystalline salt with the chemical formula Na₂MoO₄, and it serves as a source of molybdenum, an essential micronutrient for plants and enzymes. 

Key uses and properties:

• Agriculture: Sodium molybdate is a crucial source of molybdenum for plants, particularly legumes, and is used to correct molybdenum deficiencies, enhance nitrogen fixation, and improve overall crop quality and yield. 

Corrosion Inhibition: It's used in central heating systems and engine coolants to prevent galvanic corrosion and can be incorporated into paints, inks, plastics, and ceramics for corrosion inhibition and stable color formation. 

Synthesis: It's a precursor for synthesizing various materials, including MoS2-based electrode materials for sodium-ion batteries and MoS2 quantum dots for fluorescence sensors. 

Other applications: Sodium molybdate is also used in the treatment of whiptail in broccoli and cauliflower, as an electrolyte additive in energy storage devices, and as an NMR chemical shift reference compound. 
Chemical Properties:

It is a white crystalline solid with a molecular weight of 205.92 g/mol. It can be synthesized by dissolving MoO3 in sodium hydroxide and crystallizing the filtered solution.

Molybdenum disulfide (MoS2) is a chemical compound composed of molybdenum and sulfur. It's a layered material with a unique structure and properties, making it useful in various applications, including lubrication, electronics, and catalysis.  Key characteristics and properties:

• Structure: MoS2 consists of layers of molybdenum atoms sandwiched between layers of sulfur atoms. 

Physical Properties: It's a silvery-black solid, often found as the mineral molybdenite. It has a high melting point (2375°C) and is relatively unreactive.

Lubrication: MoS2 is widely used as a dry lubricant due to its low friction and robustness. 

Semiconductor: It can act as a semiconductor, particularly in its monolayer form where it exhibits a direct bandgap. 

2D Material: MoS2 is a two-dimensional (2D) material, meaning it can be exfoliated into single-layer or few-layer nanosheets. 

Applications: Beyond lubrication, MoS2 is explored for use in nanoelectronics, sensors, and catalysis, especially for hydrogen evolution. 

Detailed aspects:

• Layers and Stacking: Bulk MoS2 is composed of stacked layers of S-Mo-S, held together by weak van der Waals forces. These layers can be mechanically or chemically exfoliated to create single-layer or few-layer MoS2 nanosheets. 

Crystalline Forms: Layered MoS2 can exist in different crystalline forms, including 2H, 1T, and 3R phases, each with varying properties. 

Electronic Properties: The electronic band structure of MoS2 is tunable, with the monolayer exhibiting a direct bandgap, making it suitable for various electronic and optoelectronic applications.

Synthesis: Various methods are used to synthesize MoS2, including top-down (e.g., mechanical exfoliation) and bottom-up approaches (e.g., chemical vapor deposition). 

Safety: MoS2 is generally considered safe, but precautions should be taken when handling it as a powder to avoid inhalation. 

Molybdic Acid

• Purity as MoO₃: 85%
• Appearance: White to cream colored powder
• Solubility: Soluble in ammonical water and caustic
• Packing: 5/ 25 kg.

Ammonium molybdate tetrahydrate is a chemical compound with the formula (NH₄)₆Mo₇O₂₄·4H₂O. It is also known as ammonium heptamolybdate tetrahydrate. It is a white, crystalline powder that is soluble in water and insoluble in alcohol. 
Key Properties and Uses:
Appearance: White, crystalline powder. 
Solubility: Soluble in water, insoluble in alcohol. 
Molecular Formula: (NH₄)₆Mo₇O₂₄·4H₂O. 
Molecular Weight: 1235.86. 

CAS Number: 12054-85-2. 

Uses: It is used as a catalyst in various reactions, including the desulfurization of thiophene. It also serves as an analytical reagent for detecting phosphates, silicates, arsenates, and lead in aqueous solutions. Additionally, it is used in electroplating, fertilizers, and the production of molybdenum metal and ceramics. In the medical field, it has been used as an analgesic. 

Preparation: It can be prepared by dissolving molybdenum trioxide in excess aqueous ammonia and then evaporating the solution at room temperature.