Write the reaction equation: S → SO2 → SO3 → H2SO4 → Na2SO4 → BaSO4

Molten sulfur burns in oxygen with the formation of a caustic colorless gas – sulfur dioxide:

S + O2 = SO2

Sulfur dioxide is oxidized by oxygen on high heating in the presence of a catalyst to sulfur trioxide:

2 SO2 + O2 = 2 SO3

Sulfuric anhydride dissolves in water to form sulfuric acid:

SO3 + H2O = H2SO4

Sulfuric acid enters into a neutralization reaction with sodium hydroxide. Water and sodium sulfate are formed:

H2SO4 + 2 NaOH = Na2SO4 + 2 H2O

Sodium sulfate when interacting with barium chloride forms a precipitate of barium sulfate and sodium chloride in solution:

Na2SO4 + BaCl2 = 2 NaCl + BaSO4