The reaction that occurs when water is added to quick lime (calcium oxide, CaO) is an exothermic reaction that produces calcium hydroxide (slaked lime, Ca(OH)₂).
Understanding the Reaction
Here's a breakdown of the process:
- Reactants: Quick lime (CaO) and Water (H₂O)
- Product: Slaked lime (Calcium hydroxide, Ca(OH)₂)
- Chemical Equation: CaO(s) + H₂O(l) → Ca(OH)₂(aq) + Heat
Why is it Exothermic?
The reaction releases a significant amount of heat. This is because the formation of the chemical bonds in calcium hydroxide releases more energy than is required to break the bonds in the reactants (calcium oxide and water). You can often observe the water boiling or steaming as the reaction proceeds.
Key Characteristics
- Heat Generation: The most noticeable characteristic is the release of heat.
- Sound: A hissing sound may be heard as the water reacts with the quick lime.
- Volume Increase: The resulting slaked lime occupies a larger volume than the original quick lime.
- Formation of Slaked Lime: The product, calcium hydroxide (slaked lime), is a white, powdery substance.
Uses of the Reaction
This reaction is fundamental to many industrial and construction processes:
- Mortar Production: Slaked lime is a key ingredient in mortar used in construction.
- Soil Stabilization: Calcium hydroxide can be used to improve the properties of certain soils.
- Chemical Production: It's a reagent in various chemical processes.
