Ammonium sulfate is an inorganic substance, chemical formula (NH4)2SO4, colorless crystals or white particles, odorless。Decomposition above 280℃。Solubility in water: 70 at 0℃.6g，100℃时103.8g。Insoluble in ethanol and acetone。0.1 mole per liter of water has a pH of 5.5。Relative density 1.77。Refractive index 1.521。Ammonium sulfate is mainly used as a fertilizer and is suitable for a variety of soils and crops。It can also be used in textile, leather, medicine and so on。

　　An excellent nitrogen fertilizer (commonly known as fertilizer powder), suitable for general soil and crops, can make branches and leaves grow vigorously, improve fruit quality and yield, enhance crop resistance to disasters, can be used as base fertilizer, topdressing and seed fertilizer。It can produce ammonium chloride by double decomposition reaction with salt, and ammonium alum by action with aluminum sulfate, and make refractory materials together with boric acid。Adding electroplating solution can increase electrical conductivity。It is also the catalyst of food sauce color, the nitrogen source of yeast culture in the production of fresh yeast, acid dye dyeing aid, leather deashing agent。In addition, it is also used in beer brewing, chemical reagents and battery production。Another important role is the mining of rare earth, the mining of ammonium sulfate as raw materials, the use of ion exchange form to exchange the rare earth elements in the mine soil, and then collect the leaching solution to remove impurities, precipitation, pressing, burning into rare earth raw ore, about 5 tons of ammonium sulfate per mining production of 1 ton of rare earth raw ore。

　　There are also many biological uses，It is mainly used in protein purification process，Because ammonium sulfate is an inert substance，It is not easy to react with other bioactive substances，Maximum protection of protein activity during purification，另外，Ammonium sulfate is extremely soluble，Can form a high salt environment，Preparation for protein precipitation and subsequent high salt purification。There is a big difference between the solubility of ammonium sulfate at 0℃ and 25℃ at normal temperature. The following is the molar concentration of ammonium sulfate at different saturation at two temperatures。