You need to specify what calcium carbonate is reacting with to get a balanced chemical equation.

Here are a few common reactions of calcium carbonate:

1. Reaction with acid (e.g., hydrochloric acid):

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)

2. Thermal decomposition:

CaCO₃(s) → CaO(s) + CO₂(g)

3. Reaction with water:

CaCO₃(s) + H₂O(l) → Ca(OH)₂(aq) + CO₂(g)

Please provide more information about the specific reaction you're interested in, and I can give you the balanced chemical equation.