Question

What happens when:
(A) Quick lime is heated with silica.
(B) Chlorine reacts with slaked lime. Write the reactions involved.

Answer 1

Hint : We know that to answer this question, you should know about slaked lime. Slaked lime is the hydrated form of the compound calcium oxide. Now try to recall its reaction with chlorine and answer this question accordingly.

Complete Step By Step Answer:
We should know that lime is the most widely used reagent in water treatment applications. It is supplied in two forms: The first one is, quick lime $\left( CaO \right)$ and the second one is slaked (or hydrated) lime $\left( Ca{{\left( OH \right)}_{2}} \right)$ When chlorine gas reacts with slaked lime it forms calcium hypochlorite along with water and calcium chloride. Calcium hypochlorite is an aqueous form due to high solubility with water and the $CaC{{l}_{2}}$ is precipitated in the form of sludge. Calcium oxide is a non-aromatic crystalline or powdery solid that, in a pure form, is white to off-grey colour. It frequently appears with a yellowish or brownish shade because of the presence of impurities, particularly iron. The compound is highly caustic.
Quicklime is heated with silica to give calcium silicate.
$Ca{{O}_{\left( s \right)}}+Si{{O}_{2\left( s \right)}}\to CaSi{{O}_{3\left( s \right)}}.$
Chlorine reacts with slaked lime to form sodium hypochlorite and calcium chloride.
$2Ca{{\left( OH \right)}_{2}}+2C{{l}_{2}}\to CaC{{l}_{2}}+Ca{{\left( OCl \right)}_{2}}+2{{H}_{2}}O$

Additional Information:
Calcium oxide $\left( CaO \right)$ is generally known as quicklime or burnt lime, it is a commonly used chemical compound. It is solid at room temperature. The broadly used word lime means calcium containing inorganic materials, in which oxides and hydroxides of calcium, magnesium, aluminium, silicon and iron are present. By contrast, quicklime precisely applies to the single chemical compound calcium oxide. But commercial lime frequently contains impurities.

Note :
Remember that the quicklime is not steady or stable and, when cooled, will suddenly react with $C{{O}_{2}}$ from the air until, all the carbon dioxide is used, and it will be completely converted back to calcium carbonate if not soaked with water to set as lime plaster or lime mortar.