|CAS number||, (decahydrate)|
|Jmol-3D images||Image 1|
|Molar mass||265.90 g mol−1|
|Melting point||988 °C (anhydrous)
79.5 °C (decahydrate)
|Solubility in water||2.61 g/100 mL (0 °C)
6.7 g/100 mL (25 °C)
42.2 g/100 mL (100 °C)
|Solubility||insoluble in ammonia, alcohol|
|Refractive index (nD)||1.425|
|Crystal structure||monoclinic (decahydrate)|
|EU Index||Not listed|
|Other anions||Trisodium phosphate
|Other cations||Tetrapotassium pyrophosphate|
|Related compounds||Disodium pyrophosphate|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Tetrasodium pyrophosphate, also called sodium pyrophosphate, tetrasodium phosphate or TSPP, is a colorless transparent crystalline chemical compound with the formula Na4P2O7. It is a salt composed of pyrophosphate and sodium ions. Toxicity is approximately twice that of table salt when ingested orally. There is also a hydrated form, Na4P2O7 · 10(H2O).
Sodium pyrophosphate is used as a buffering agent, an emulsifier, a dispersing agent, and a thickening agent, and is often used as a food additive. Common foods containing sodium pyrophosphate include chicken nuggets, marshmallows, pudding, crab meat, imitation crab, canned tuna, and soy-based meat alternatives and cat foods and cat treats where it is used as a palatability enhancer. It is the active ingredient in Bakewell, the substitute for baking powder's acid component marketed during shortages in World War II. It is also used in some common baking powders.
In toothpaste and dental floss, sodium pyrophosphate acts as a tartar control agent, serving to remove calcium and magnesium from saliva and thus preventing them from being deposited on teeth. Tetrasodium pyrophosphate is used in commercial dental rinses before brushing to aid in plaque reduction.