Question

The reaction between quicklime and water is characterized by:
(This question has multiple correct options)
(A) Evolution of hydrogen gas
(B) Suspension of slaked lime in water
(C) Change in temperature of the mixture
(D) Change in colour of the product

Answer 1

Hint: Quicklime is another name used for calcium oxide. When this is treated with water calcium hydroxide will be formed. Calcium hydroxide in a solid-state is usually called by another name and the product is used in the whitewashing of walls.

Complete step by step solution:
-As we know quick lime is calcium oxide with the chemical formula $CaO$. It's also known as burnt lime and is a white, crystalline, caustic, alkaline solid at the room temperature.
-When calcium oxide or quick lime is heated in an oxyhydrogen flame, a white light usually called limelight is emitted. When the quicklime is added to caustic soda or sodium hydroxide, a solid named soda lime is formed.
-We are asked about the reaction between quicklime and water. Calcium oxide is normally found in the lump form. When we add a limited amount of water, these lumps will break down along with a hissing sound. A large amount of heat is evolved during this process and the water gets converted into steam. The corresponding reaction between water and calcium oxide can be written as follows
$CaO+{{H}_{2}}O\to Ca{{(OH)}_{2}}+Heat$
-We obtain a fine powder as a product which is calcium hydroxide ($Ca{{(OH)}_{2}}$) or slaked lime and we can call this process of formation of slaked lime as slaking of lime.
-As we can see the quicklime or calcium oxide in reaction with water, a suspension of slaked lime in water is formed as the product along with the evolution of heat energy and the temperature of the reaction mixture is changed by this heat energy.

Therefore, the answers are options (B) and (C).

Note: It should be noted that calcium oxide is a basic oxide and as a result, it combines with acidic oxides and acids at the higher temperature to produce the corresponding salts. Also, there might be confusion among the names: Quicklime is calcium oxide ($CaO$), slaked lime is the calcium hydroxide ($Ca{{(OH)}_{2}}$) in solid-state and lime water is a dilute solution of calcium hydroxide.