The key difference between calcium carbonate and calcium oxide is that calcium carbonate tends to undergo decomposition upon heating to high temperatures, whereas calcium oxide is very stable towards heat treatment.
Calcium carbonate and calcium oxide are important inorganic compounds of calcium metal. These substances have various applications in industries.
CONTENTS
1. Overview and Key Difference
2. What is Calcium Carbonate
3. What is Calcium Oxide
4. Side by Side Comparison – Calcium Carbonate vs Calcium Oxide in Tabular Form
5. Summary
What is Calcium Carbonate?
Calcium carbonate is a carbonate of calcium that has the chemical formula CaCO3. This compound naturally occurs as limestone, chalk, calcite, etc. Therefore, it is a common substance in rocks. Ex: calcite or aragonite (Limestone contains both these forms). Calcium carbonate occurs as white hexagonal crystals or powder, and it is odourless.
Figure 01: Appearance of Calcium Carbonate
Moreover, Calcium carbonate has a chalky taste. The molar mass of this compound is 100 g/mol, and the melting point is 1,339 °C (for the calcite form). However, it has no boiling point because this compound decomposes at high temperatures. We can get this compound by mining the calcium-bearing minerals. But this form is not pure. We can obtain a pure form using a pure quarried source such as marble. When calcium carbonate reacts with acids, it forms CO2 gas. When it reacts with water, it forms calcium hydroxide. In addition to these, it can undergo thermal decomposition, releasing CO2 gas.
What is Calcium Oxide?
Calcium oxide is an inorganic compound having the chemical formula CaO. It is also named quicklime or burnt lime. We can describe this substance as a white, caustic, alkaline, and crystalline compound. It is odourless as well.
Figure 02: Appearance of Calcium Oxide
Concerning the preparation of calcium oxide, this substance is usually manufactured by the thermal decomposition of limestone or seashells containing calcium carbonate in a lime kiln. In this preparation process, we need to heat the reactants to above 625 Celsius degree temperature. This heat treatment is called calcination. This process releases molecular carbon dioxide, which leaves quicklime. Since quicklime is not stable, it can spontaneously react with carbon dioxide when cooled, and after a sufficient time, it will completely convert back to calcium carbonate. Therefore, we need to slack it with water to set it as lime plaster or lime mortar.
When considering the uses of calcium oxide, the major use is in the basic oxygen steelmaking process, where it can neutralize the acidic oxides, silicone oxide, aluminum oxide and ferric oxide, producing a molten slag. Another important application of calcium oxide is using it in the production of aerated concrete blocks having varying densities.
What is the Difference Between Calcium Carbonate and Calcium Oxide?
Calcium carbonate is a carbonate of calcium that has the chemical formula CaCO3, while Calcium oxide is an inorganic compound having the chemical formula CaO. The key difference between calcium carbonate and calcium oxide is that calcium carbonate tends to undergo decomposition upon heating to high temperatures, whereas calcium oxide is very stable towards heat treatment.
Below is a summary of the differences between calcium carbonate and calcium oxide in tabular form.
Summary – Calcium Carbonate vs Calcium Oxide
Calcium carbonate and calcium oxide are important inorganic compounds of calcium metal. The key difference between calcium carbonate and calcium oxide is that calcium carbonate tends to undergo decomposition upon heating to high temperatures, whereas calcium oxide is very stable towards heat treatment.
Reference:
1. Giammaria, Guido, and Leon Lefferts. “Catalytic Effect of Water on Calcium Carbonate Decomposition.” Journal of CO2 Utilization, Elsevier, 4 July 2019, Available here.
Image Courtesy:
1. “Calcium carbonate” By Picture taken August 2005 by User:Walkerma (Public Domain) via Commons Wikimedia
2. “Calcium oxide powder” By Leiem – Own work (CC BY-SA 4.0) via Commons Wikimedia