Slaking of lime refers to_________
- AMixing NaCl in hydraulic lime
- BMixing water in quick limeCorrect
- CMixing water in limestone
- DMixing NaCl in quick limeM
Solution
Concept
Hydration of calcium oxide (quick lime) to form calcium hydroxide (slaked lime) through the addition of water.
Formula
CaO + H2O -> Ca(OH)2 + Heat
Step-by-step solution
1. Identify the input material: Quick lime is chemically calcium oxide (CaO). 2. Understand the process of slaking: Water is added to quick lime to prepare it for construction use. 3. Write the chemical reaction: CaO + H2O = Ca(OH)2 with evolution of heat. 4. Conclude that slaking refers to mixing water in quick lime.
Explanation
Slaking of lime is the exothermic process in which water is added to quick lime (calcium oxide, CaO). This chemical reaction converts quick lime into slaked lime or hydrated lime (calcium hydroxide, Ca(OH)₂), releasing a large amount of heat.
Why the other options are wrong
A: NaCl has no role in slaking hydraulic lime. C: Limestone undergoes calcination (heating), not slaking, when mixed with water (limestone does not react with water). D: NaCl is not added to quick lime for slaking.
Shortcut
Quick lime + Water = Slaked lime (Hydration).
Common mistake
Confusing quick lime (CaO) with limestone (CaCO3), which is the raw material used to manufacture quick lime by calcination.
Correct answer: B) Mixing water in quick lime