hydrogensulfite sulfonic acid sulfur oxoacid sulfurous acid acido sulfuroso trioxosulfuric acid 81.97247 CHEBI:9344 acide sulfureux Sulfurous acid dihydroxidooxidosulfur OS(O)=O CAS:7782-99-2 schweflige Saeure H2SO3 dihydrogen trioxosulfate 82.08008 Gmelin:1458 KNApSAcK:C00019662 CHEBI:26837 InChI=1S/H2O3S/c1-4(2)3/h(H2,1,2,3) [SO(OH)2] UM-BBD_compID:c0348 PDBeChem:SO3 sulfurous acid LSNNMFCWUKXFEE-UHFFFAOYSA-N 0 S(O)(OH)2 sulphurous acid CHEBI:48854 Sulfite KEGG:C00094 chebi_ontology H2O3S