The equation BaCO3 + SO2 + H2O -> BaHSO4 + CO2

This equation describes the chemical reaction process between BaCO₃ (Barium carbonate), SO₂ (sulfur dioxide), and H₂O (water) to produce BaHSO₄ (Barium hydrosulfate) and CO₂ (carbon dioxide). This equation has been balanced, meaning the number of atoms for each element on both sides of the equation are equal.

Reaction condition: The reaction needs to occur in the presence of high temperature and pressure. Specifically, the temperature needs to be at a level sufficient to decompose BaCO₃ and allow SO₂ to react with BaCO₃.

Reaction process: When Barium carbonate (BaCO₃) is placed in an environment containing sulfur dioxide (SO₂) and water (H₂O) with appropriate temperature and pressure conditions, it will react and produce Barium hydrosulfate (BaHSO₄) and carbon dioxide (CO₂).

Occurring phenomena: During the reaction process, changes in color or state of the reactants can be observed. For example, BaCO₃ is white and during the reaction, it may turn into the color of BaHSO₄. In addition, the release of CO₂ gas can be observed.