Question

In the presence of cobalt chloride $\left( {{\text{CoC}}{{\text{l}}_{\text{2}}}} \right)$, bleaching powder decomposes to form:
A) ${\text{CaC}}{{\text{O}}_{\text{3}}}$
B) ${\text{CaOC}}{{\text{l}}_{\text{2}}}$
C) ${\text{C}}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{8}}}$
D) ${\text{CaC}}{{\text{l}}_{\text{2}}}$

Answer 1

Hint: To solve this we must know the chemical formula for bleaching powder. The chemical name for bleaching powder is calcium hypochlorite. The chemical formula for calcium hypochlorite is ${\text{CaOC}}{{\text{l}}_{\text{2}}}$. Bleaching powder is pale yellow coloured powder and it has a strong smell of chlorine.


Complete solution:
We know that the chemical name for bleaching powder is calcium hypochlorite. The chemical formula for calcium hypochlorite is ${\text{CaOC}}{{\text{l}}_{\text{2}}}$. Bleaching powder is pale yellow coloured powder and it has a strong smell of chlorine.
Cobalt chloride $\left( {{\text{CoC}}{{\text{l}}_{\text{2}}}} \right)$ is a pink to red coloured powder which has a slightly sharp odour.
The reaction of bleaching powder i.e. calcium hypochlorite with cobalt chloride is as follows:
${\text{2CaOC}}{{\text{l}}_{\text{2}}}\xrightarrow{{{\text{CoC}}{{\text{l}}_2}}}2{\text{CaC}}{{\text{l}}_2} + {{\text{O}}_2}$
In presence of cobalt chloride, bleaching powder loses its oxygen and gets converted to calcium chloride.
In this reaction, cobalt chloride acts as a catalyst which liberates oxygen. When cobalt chloride is kept in contact with bleaching powder for a longer time calcium chlorate and calcium chloride ${\text{Ca}}{\left( {{\text{Cl}}{{\text{O}}_{\text{3}}}} \right)_{\text{2}}}$ are formed.
Thus, from the reaction we can see that in the presence of cobalt chloride $\left( {{\text{CoC}}{{\text{l}}_{\text{2}}}} \right)$, bleaching powder decomposes and form calcium chloride and oxygen gas is released as a by-product.
Thus, in the presence of cobalt chloride $\left( {{\text{CoC}}{{\text{l}}_{\text{2}}}} \right)$, bleaching powder decomposes to form ${\text{CaC}}{{\text{l}}_{\text{2}}}$.

Thus, the correct option is (D) ${\text{CaC}}{{\text{l}}_{\text{2}}}$.


Note: Bleaching powder is soluble in water. It is prepared from dry slaked lime which reacts with chlorine gas. Bleaching powder is used for bleaching dirty clothes that are made of cotton and linen. Bleaching powder is a strong oxidising agent. It is also used as a disinfectant.