Combination reactions occur when two or more substances (elements or compounds) combine to form a single product.

When slaked lime reacts with carbon dioxide in the air, calcium carbonate (CaCO3) is formed.

The formation of calcium carbonate on whitewashed walls creates a shiny finish by reflecting light uniformly. It fills imperfections, enhancing the walls’ appearance, contributing to their smooth and glossy look.

The chemical formula for marble is also CaCO3. This indicates that the calcium carbonate formed on whitewashed walls is chemically similar to the material of marble.

The reaction of calcium oxide with water is exothermic, meaning it releases a large amount of heat.