... .Monthly output: about 3000MT 4.CAS No.:7681-57-4 sodium metabisulfite (1)Molecular formula: Na2S2O5 (2)CAS No.: 7681-57-4 ... : 2ppm max ,pH: 4.0-4.6(5)Bag marks:Sodium metabisulphite, N.W.: 25kgs, G.W. 25.1kgs, Made in ... , Tangshan, ChinaWebsite: www.tssjhg.com.cnTel/fax:0086-315-2239987 sodium metabisulfite