Calcium oxide, also known as quicklime, reacts with the air by absorbing moisture and carbon dioxide. This process leads to the formation of calcium hydroxide and calcium carbonate.
The Chemical Reactions
The reference provided outlines the two primary reactions:
-
Reaction with Carbon Dioxide: Calcium oxide (CaO) reacts with carbon dioxide (CO2) in the air to produce calcium carbonate (CaCO3).
CaO + CO2 --> CaCO3 -
Reaction with Water: Calcium oxide (CaO) also reacts with water (H2O) from the air to form calcium hydroxide (Ca(OH)2). This process is known as slaking of lime.
CaO + H2O --> Ca(OH)2
Summary of Reactions
| Reactant 1 | Reactant 2 | Product | Chemical Formula |
|---|---|---|---|
| Calcium Oxide | Water | Calcium Hydroxide | CaO + H2O --> Ca(OH)2 |
| Calcium Oxide | Carbon Dioxide | Calcium Carbonate | CaO + CO2 --> CaCO3 |
Understanding the Process
- Absorption: When calcium oxide is exposed to the atmosphere, it starts absorbing moisture (water vapor) and carbon dioxide from the air.
- Slaking of Lime: The reaction with water to form calcium hydroxide is an exothermic reaction, meaning it releases heat. If limited water is used, the lump of lime breaks down, this is called slaking.
- Carbonation: The reaction with carbon dioxide leads to the formation of calcium carbonate, a common component of limestone and marble.
Practical Implications
- Building Materials: These reactions are essential in understanding how lime behaves when used in construction, particularly in mortar and plaster.
- Industrial Uses: Calcium oxide is used in many industrial applications, and its reactivity with air needs to be accounted for in storage and handling.
