Molecular Formula: (NH4)2SO4 Molecular Weight: 132.13 Physicochemical Properties: white crystal. Product Specification: GB/T19001-2000 Major indexes of agricultural and industrial grade: 1) Nitrogen: 21.0; 21.0pct min 2) Moisture: 0.5;0.5pct max 3) Free acid (H2SO4): 0.05; 0.05pct max 4) Ferric: 0.007; ---pct max 5) Arsenic: 0.0005; ---pct max 6) Heavy metal (based on Pb): 0.005; ---pct max 7) Water insoluble: 0.05; ---pct max Packing: 25 kg/bag, plastic inside and knitting bag outside, or in terms of customer's requirement.