When excess carbon dioxide is passed through calcium carbonate, a series of chemical reactions occur, leading to the formation of calcium bicarbonate. Here’s a detailed explanation of the process:

Reaction Overview
- Calcium carbonate (CaCO₃) is a stable compound commonly found in limestone and marble.
- When excess carbon dioxide (CO₂) is introduced, it reacts with calcium carbonate.

Chemical Reaction
- The primary reaction can be represented as:
**CaCO₃ (s) + CO₂ (g) + H₂O (l) ⇌ Ca(HCO₃)₂ (aq)**
- This reaction shows that calcium carbonate reacts with water and carbon dioxide to form calcium bicarbonate.

Formation of Calcium Bicarbonate
- Calcium bicarbonate (Ca(HCO₃)₂) is soluble in water, unlike calcium carbonate.
- This solubility allows calcium bicarbonate to remain in the aqueous phase, making it easier for the carbon cycle and geological processes.

Applications and Implications
- **Water Hardness**: The formation of calcium bicarbonate contributes to water hardness in natural water bodies.
- **Carbon Sequestration**: This process can be an important aspect of carbon capture technologies aimed at reducing atmospheric CO₂ levels.
- **Soil Chemistry**: The reaction impacts soil pH and nutrient availability, influencing agricultural practices.

Conclusion
- Passing excess CO₂ through calcium carbonate leads to the formation of calcium bicarbonate, which has significant implications in environmental science and chemistry. Understanding this reaction is crucial for addressing issues related to climate change and resource management.