Question

Quicklime$\left(CaO\right)$ is mixed with water to prepare a solution used for whitewashing the walls in our home. What is the common chemical name of the product generated by this mixture? After the whitewash is done $\left(C{O}_2\right)$ in the atmosphere causes the white color to intensify. Write a chemical reaction to explain how this happens.

Answer 1

1. Combination reaction: A reaction in which two or more compound combines to form a single compound.
2. When quicklime $\left(CaO\right)$ is mixed with water, calcium hydroxide is obtained. This obtained calcium hydroxide $\left(Ca{\left(OH\right)}_2\right)$ known as slaked lime is used for a whitewash in our homes.
3. The chemical reaction for the formation of slaked lime is as follows:

$\underset{\underset{(Quicklime)}{\underbrace{(Calciumoxide)}}}{\underbrace{CaO\left(s\right)}}+\underset{\left(Water\right)}{\underbrace{H_{2}O\left(l\right)}}\to \underset{\underset{(Slakedlime)}{\underbrace{(Calciumhydroxide)}}}{\underbrace{Ca{\left(OH\right)}_2\left(aq\right)}}$

Setting of Slaked lime:

1. When the whitewash is done, the$\left(C{O}_2\right)$ in the atmosphere causes the whitewash to intensify, This is because $\left(C{O}_2\right)$ reacts with the slaked lime forming Calcium carbonate $\left(CaC{O}_3\right)$ which is milky white in color.
2. The chemical reaction for the above process is as follows :

$\underset{(Slakedlime)}{\underbrace{Ca{\left(OH\right)}_2\left(aq\right)}}+\underset{(Carbondioxide)}{\underbrace{C{O}_2\left(g\right)}}\to \underset{(Calciumcarbonate)}{\underbrace{CaC{O}_3\left(s\right)}}+\underset{\left(Water\right)}{\underbrace{H_{2}O\left(l\right)}}$

The obtained calcium carbonate intensifies the whitewash.