Question

When water is added to quicklime, the rise in temperature is observed. This is an example of _____ reaction.

Answer 1

Hint: Quicklime is the common name of calcium oxide. It is represented by the chemical formula $ CaO $. It is a whitish, odourless alkaline substance. Under standard conditions for temperature and pressure, quicklime is said to exist as a white to pale yellow powder. It also exists as a pale brown coloured compound.

Complete answer:
When we add water in quicklime, a sudden rise in temperature is observed. Hence, this is an example of exothermic reaction
An exothermic reaction is defined as a reaction in which energy is released in the form of light or heat. We can say that in an exothermic reaction, energy is transferred into the surroundings. In an exothermic reaction, energy is released as the total energy of the products is less than the total energy of the reactants.
When water is added to quicklime, calcium hydroxide is obtained with the evolution of heat. There is a rise in temperature. Calcium hydroxide is also known as slaked lime.
The reaction that takes place is as follows:
$ CaO + {H_2}O \to Ca{(OH)_2} + \text{Heat} $
Hence, when water is added to quicklime, the rise temperature is observed. This is an example of an exothermic reaction.

Additional Information:
Quicklime is also known as handpicked lime, burnt lime, lump lime, calcining lime, and caustic lime. It is known as a caustic material that is prepared at approximately $ 900 $ degrees Celsius by burning calcium carbonate limestone, carbon dioxide is forced off at this high temperature, and the limestone is converted to Quicklime.

Note:
In an exothermic reaction, the enthalpy change will be negative. The chemical reactions that proceed with the evolution of heat are called exothermic reactions whereas the reactions which proceed with the absorption of heat are called endothermic reactions.