Colorless or slightly yellowish monoclinic crystal compound . 1, Chemical name: Sodium Thiosulfate 2, Structural formula: 3, Molecular formula: Na2S2O2·5H2O4, Molecular weight: 248.175, Properties: monoclinic crystal, Melting point : 40-45, Relative density :1.729(17). 6, Quality standard:ItemUnitPhotographic gradeIndustrial gradeAnhydrous gradeAppearance colorless transparent crystalwhite ...