THERMAL-DECOMPOSITION OF SODIUM-CARBONATE PERHYDRATE IN THE SOLID-STATE

On heating sodium carbonate perhydrate under vacuum, ∼360-410 K, the constituent hydrogen peroxide decomposed as follows: Na2CO3·1.5H2O2 → Na2CO3 + 1.5H2O + 0.75O2. Fractional decomposition (α)-time curves were sigmoid shaped. The reaction rate in 20 torr water vapor was appreciably less than that under vacuum, behavior which markedly contrasts with the large increase in rate found when liquid water was present. It is concluded that the water accelerates the solid state reaction and escape of this product is opposed by the presence of an effective barrier phase of anhydrous Na2CO3 product. When water vapor was available the residual product was reorganized and the opening of channels permitted the escape of water, with a consequent reduction in the overall reaction rate. © 1979 American Chemical Society.