Na2SO4 + CaCO3 + 4C → A–– + B–– + 4CO, A & B are
& respectively
Na2SO4 + CaCO3 + 4C → CaS + Na2CO3 + 4CO
When sodium sulphate reacts with calcium carbonate in presence of carbon will give rise to calcium sulphide, sodium carbonate with release of carbon monoxide.