Sodium pyrosulfate

Sodium pyrosulfate is an inorganic compound with the chemical formula of Na2S2O7. It is a colorless salt. It hydrolyses in water to form sodium bisulfate with a chemical formula of NaHSO4 which has a pH of around 1.

Preparation
Sodium pyrosulfate is obtained by the dehydration of sodium bisulfate:


 * 2 NaHSO4 → Na2S2O7 + H2O

Temperatures above 460 °C further decompose the compound, producing sodium sulfate and sulfur trioxide:


 * Na2S2O7 → Na2SO4 + SO3

Applications
Sodium pyrosulfate was used in analytical chemistry. Samples are fused with sodium pyrosulfate to ensure complete dissolution before a quantitative analysis.