1. Decomposition: When calcium carbonate (CaCO3) is heated to a sufficiently high temperature, it undergoes thermal decomposition. This means it breaks down into calcium oxide (CaO) and carbon dioxide (CO2) gas. The chemical reaction can be represented as:
CaCO3 -> CaO + CO2
2. Solid to Solid Transformation: As calcium carbonate decomposes, the solid calcium carbonate gradually transforms into solid calcium oxide. Calcium oxide is also known as quicklime.
3. Loss of Mass: During decomposition, carbon dioxide gas is released, which results in a loss of mass in the overall system. Calcium oxide has a lower molecular weight than calcium carbonate, so the remaining solid will be lighter in weight.
4. Increased Porosity: The release of carbon dioxide gas creates pores and voids within the solid calcium oxide, making it more porous.
5. Change in Color: Calcium carbonate is typically white, while calcium oxide appears grayish-white or pale yellow. This change in color is due to the loss of carbon dioxide and the formation of different chemical bonds.
6. Increased Reactivity: Calcium oxide is more reactive than calcium carbonate. It readily reacts with water, releasing heat and forming calcium hydroxide [Ca(OH)2]. This exothermic reaction is known as slaking.
In summary, heating calcium carbonate causes it to decompose and transform from solid calcium carbonate to solid calcium oxide. It experiences a loss of mass, becomes more porous, changes color, and increases in reactivity.
