The main difference between calcium oxide and calcium hydroxide is that calcium oxide is formed by heating calcium carbonate, whereas calcium hydroxide is formed by adding water to calcium oxide.
Calcium oxide (CaO) and calcium hydroxide (Ca(OH)₂) are both compounds of calcium, but they differ in terms of their chemical composition, properties, and uses.
Key Areas Covered
1. What is Calcium Oxide
– Definition, Formation, Properties
2. What is Calcium Hydroxide
– Definition, Formation, Properties
3. Similarities Between Calcium Oxide and Calcium Hydroxide
– Outline of Common Features
4. Difference Between Calcium Oxide and Calcium Hydroxide
– Comparison of Key Differences
Key Terms
Burnt Lime, Calcium Oxide, Calcium Hydroxide, Hydrated Lime, Quicklime, Slaked Lime
What is Calcium Oxide
Calcium oxide (quicklime or burnt lime) is a white, crystalline solid with the chemical formula CaO. It is formed through calcination, which involves heating calcium carbonate (CaCO₃) at high temperatures. This process releases carbon dioxide (CO₂) and leaves behind calcium oxide. The resulting compound has a high melting point and low solubility in water.
One of the most notable properties of calcium oxide is its reactivity with water. When water is added to calcium oxide, an exothermic reaction occurs. It generates heat and produces calcium hydroxide (Ca(OH)₂). This reaction, called slaking or hydration, can be hazardous if not handled properly. Moreover, the heat generated during the reaction can be utilized in applications such as heating water or generating steam.
The reactivity of calcium oxide extends beyond its interaction with water. It also reacts vigorously with acids, resulting in the formation of calcium salts. This property also makes calcium oxide useful in various chemical processes and industries, including the production of calcium-based chemicals.
Applications of Calcium Oxide
The applications of calcium oxide are diverse and wide-ranging. In the construction industry, it is utilized as an essential component of mortar and plaster, providing strength and stability to structures. Calcium oxide can also be combined with sand to produce a material known as lime mortar, which has been used for centuries in the construction of historic buildings and monuments.
Furthermore, calcium oxide plays a crucial role in steel production. It is used as a fluxing agent, facilitating the removal of impurities and enhancing the quality of the final product. Calcium oxide reacts with acidic impurities, forming slag that can be easily separated from molten steel. This process, known as steel desulfurization, is vital in producing high-quality steel.
What is Calcium Hydroxide
Calcium hydroxide, or slaked lime or hydrated lime, is a compound used for centuries due to its unique properties and versatile applications. Calcium hydroxide has a chemical formula of Ca(OH)₂, indicating that it consists of one calcium atom (Ca) bonded to two hydroxide ions (OH⁻). It is formed by adding water to calcium oxide (CaO) in a process known as slaking or hydration. Furthermore, this reaction is highly exothermic, releasing heat as calcium oxide reacts with water to form calcium hydroxide.
The resulting compound is a white powder or colorless crystal with a lower melting point than calcium oxide. Calcium hydroxide is relatively more soluble in water than calcium oxide. When added to water, it forms a saturated solution known as lime water.
One of the key characteristics of calcium hydroxide is its alkaline nature. It is classified as a strong base and readily reacts with acids to form calcium salts. This property makes calcium hydroxide useful in various chemical processes, such as pH regulation and neutralization reactions.
Calcium hydroxide has extensive applications in the construction industry. It is commonly used in the preparation of lime mortar and lime plaster. Lime mortar, made by mixing calcium hydroxide with sand, has been used for centuries to construct buildings and historical monuments. Moreover, it provides excellent workability, allowing for easy application and long-term durability.
Similarities Between Calcium Oxide and Calcium Hydroxide
- Calcium oxide and calcium hydroxide contain calcium as the central element in their chemical compositions.
- Moreover, both compounds originate from calcium carbonate (CaCO₃).
- Both compounds serve as sources of calcium in various applications.
- In addition, calcium oxide and calcium hydroxide exhibit alkaline properties.
Difference Between Calcium Oxide and Calcium Hydroxide
Definition
Calcium hydroxide (Ca(OH)₂), also known as slaked lime or hydrated lime, is a chemical compound composed of one calcium atom (Ca) and two hydroxide ions (OH⁻). On the other hand, calcium oxide (CaO), also known as quicklime or burnt lime, is a chemical compound composed of one calcium atom (Ca) and one oxygen atom (O).
Formation
Calcium oxide is produced by heating calcium carbonate (CaCO₃) at high temperatures. However, calcium hydroxide is formed by adding water to calcium oxide in a process called slaking or hydration.
Physical Properties
Moreover, calcium oxide is a white, crystalline solid with a high melting point. Furthermore, it has low solubility in water and is not very reactive with atmospheric moisture. Meanwhile, calcium hydroxide exists as a white powder or colorless crystal. It has a lower melting point than calcium oxide and is relatively more soluble in water.
Conclusion
The main difference between calcium oxide and calcium hydroxide is that calcium oxide forms by heating calcium carbonate, while calcium hydroxide forms by adding water to calcium oxide. Moreover, calcium oxide is a white, crystalline solid with a high melting point and low solubility in water. It is not highly reactive with atmospheric moisture. On the other hand, calcium hydroxide is a white powder or colorless crystal. In addition, it has a lower melting point than calcium oxide and is relatively more soluble in water.
Reference:
1. “Quicklime | Formula, Uses, & Definition.” Encyclopedia Britannica.
2. “Calcium hydroxide | Definition, Formula, Uses, Properties, & Facts.” Encyclopedia Britannica.
Image Courtesy:
1. “Calcium-oxide-3D-vdW” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia
2. “Calcium hydroxide” – Picture taken by w:User:Walkerma in June 2005. – Own work (Public Domain) via Commons Wikimedia
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