Ammonium thiosulfate, universally identified by its CAS number 7783-18-8, is a chemical compound of significant industrial and photographic importance. Its distinct properties and reactivity profile make it a valuable agent in a variety of applications, from developing photographic images to facilitating industrial chemical processes. Understanding the specifics of this compound, including its ammonium thiosulfate chemical properties, is key to leveraging its full potential. Physically, ammonium thiosulfate typically appears as colorless or light yellow crystals. It is characterized by an ammoniacal odor. Its molecular formula is (NH4)2S2O3, and it has a molecular weight of 148.20500. A notable characteristic is its hygroscopic nature, meaning it attracts and holds water molecules from the surrounding atmosphere. This property dictates that it should be stored in tightly sealed containers to prevent caking and maintain its purity and efficacy. The compound's solubility in water is excellent, which is fundamental to its use in aqueous solutions for photographic fixers and other chemical applications. Its solubility in acetone is slight, and it is insoluble in ethanol and diethyl ether, providing a degree of selectivity in its chemical behavior. In the realm of photography, ammonium thiosulfate is highly regarded as a photographic fixer. Its rapid action, often compared favorably in ammonium thiosulfate vs sodium thiosulfate discussions, allows for quicker processing times, especially with modern films which are often rich in iodide. This efficiency contributes to its widespread adoption as an ammonium thiosulfate photographic fixer. Beyond photography, the ammonium thiosulfate industrial applications are extensive. It serves as a metal cleaner, an electroplating solution component, and a reducing agent in various chemical syntheses. These diverse uses highlight the compound's versatility and its importance in manufacturing and production. When sourcing ammonium thiosulfate, the CAS 7783-18-8 ensures precise identification. Its melting point of 180°C (with decomposition) and density of 1.679 g/mL at 25°C provide critical data points for handling and formulation. In essence, ammonium thiosulfate (CAS 7783-18-8) is a multifaceted chemical. Whether utilized for its precise function as an ammonium thiosulfate photographic fixer or for its broader ammonium thiosulfate industrial applications, a thorough understanding of its properties and handling is paramount for successful outcomes.