Sodium citrate refers to the trisodium salt of citric acid in common usage, which has the chemical formula C6H5Na3O7. There are a total of three possible sodium salts of citric acid possessing the chemical formula C6H(8-x)Na(x)O7, where x is between one and three.
Since citric acid is a triprotic acid, it can form a total of three salts with sodium: monosodium citrate, disodium citrate, and trisodium citrate. Trisodium citrate is commonly used as in food as a flavoring and preservative. It is also employed as a buffering agent in scientific research, and in the medical field as a blood anticoagulant.