When heated calcium sulfite decomposes to form calcium oxide and sulfur dioxide?

Answer 1

Under very specific circumstances it can, however, the normal reaction between CaSO3 and heat in the presence of O2 (in air, for example) is to create CaSO4. A good example is the dry lime flue gas desulfurization process. In a non-forced oxidation process, CaO (lime) readily reacts with SO2 forming CaSO3 in flue gas, which is then recovered as a solid. With added oxygen (the forced oxidation process), the CaSO3 in the flue gas oxidizes to CaSO4, which is then recovered as a solid.

In air, even at room temperatures, CaSO3 slowly oxidizes to CaSO4.

That said, in order to get from CaSO3 to CaO and SO2, you have to heat it under reducing conditions to drive off the oxygen, creating CaS, cleave the Ca-S bond, then perform an oxidation reaction to form recoverable CaO and SO2.

Answer 2

When calcium sulfite is heated, it decomposes to form calcium oxide (CaO) and sulfur dioxide (SO2). This decomposition reaction is a chemical change in which the compound breaks down into simpler substances upon heating.