What happens when ammonium sulfate is heated

Ammonium sulfate (NH4)2SO4

White, crystalline

In the soil from fertilizer salts

molar mass 132.140 g / mol

AGWnot specified
decomposition +280 ° C  
density 1.77 g / cm3   
Water solubility 
100g H2O dissolve 75.44 g at 20 ° C

Hazard classes + category 
HP rates(See note)    
disposal Residual waste or sewage
print a labelGerman nameEnglish name
CAS7783-20-2Ammonium sulfateAmmonium sulfate


The clear ammonium sulfate crystals, which appear white when finely divided, dissolve well in water with a slightly acidic reaction. When heated to 235 ° C, the ammonia gas is split off with the formation of ammonium hydrogen sulfate. On further heating above the decomposition point of 280 ° C, the intermediate product also decomposes to ammonium disulphate (NH4)2S.2O7 . When mixed with nitrites, the decomposition can take place explosively.

Ammonium sulfate as a crystalline powder


Ammonium sulfate is formed when ammonia is introduced into sulfuric acid in a strongly exothermic reaction. The sulfuric acid is diluted with water so that the reaction does not turn out too violent. With a sulfuric acid concentration of over 70%, so much heat is generated that the water evaporates by itself. After careful evaporation, the crystalline salt is obtained:
2 NH3 + H2SO4  (NH4)2SO4


Due to its nitrogen content, ammonium sulfate is one of the most important salts used in the manufacture of fertilizers. It is also used for this purpose together with ammonium nitrate. Ammonium sulfate is approved as a food additive E 517 for carrier substances. It is also suitable as a flame retardant in paper production or as a nutrient salt for the cultivation of microorganisms, for example yeasts.