The chemical reaction between calcium oxide (CaO) and carbon dioxide (CO₂) combines to form calcium carbonate (CaCO₃). The balanced chemical equation for this reaction is:
\[ \text{CaO} + \text{CO}_2 \rightarrow \text{CaCO}_3 \]
In this reaction, neither matter is created nor destroyed; rather, it is conserved as the reactants combine to form the product, calcium carbonate.