Question

How can quicklime be prepared from slaked lime?
A. By cooling slaked lime
B. By heating slaked lime
C. By adding water
D. None of these

Answer 1

Calcium hydroxide is the IUPAC name of slaked lime and calcium oxide is called quick lime.
The molecular formula of calcium hydroxide is $Ca{{(OH)}_{2}}$ and the molecular formula of calcium oxide is $CaO.$

Complete step by step answer:
- Calcium hydroxide is an inorganic compound and it can be prepared by adding water to quicklime.
- Adding water to quick lime is called slaking that is why calcium hydroxide is called slaked lime.
- The chemical reaction of preparation of quick lime is as follows.
$\underset{\text{Slaked lime }}{\mathop{Ca{{(OH)}_{2}}}}\,\xrightarrow{{{512}^{o}}C}\underset{\text{Quick lime }}{\mathop{CaO}}\,+{{H}_{2}}O$
- In the above reaction calcium hydroxide converts to calcium oxide (quick lime) by heating at 512 $^{o}C$ .
- Therefore quicklime can be prepared by heating slaked lime.

- So, the correct option is B.

Additional information:
- Slaked lime is used in the preparation of ammonia.
- Slaked lime is used in the sugar purification.
- Slaked lime also used to remove hardness causing salts from hard water.
- Calcium oxide or quicklime can be prepared by a calcination process.
- In the calcination process calcium carbonate or limestone is heated at 1200 $^{o}C$ .
- Calcium carbonate decomposes at 1200 $^{o}C$ and forms quicklime and carbon dioxide as the products.

Note: Calcium hydroxide is basic in nature. Calcium oxide is a white, alkaline solid at room temperature.
Now a day’s slaked lime is used in industries related to food, in medicinal fields due to its vast applications.