Question

Oxidation number of chlorine atoms in $CaOC{{l}_{2}}$ are:
(1) 0, 0
(2) -1, -1
(3) -1, +1
(4) -2, +7

Answer 1

Hint: The answer to this question depends on the calculation of oxidation state of the two types of chlorine atoms present in the given compound and based on this calculation of oxidation states is done that is total number of electrons that an atom gains or loses.

Complete Solution :
We have studied the calculation of oxidation states of the given compound by the definition of oxidation states in the classes of chemistry.
Now, we shall see the calculation of oxidation state of this compound that is $CaOC{{l}_{2}}$
- the compound given that is $CaOC{{l}_{2}}$ is commonly called as bleaching powder and therefore has the chemical name as calcium hypochlorite.
- Here, in this compound, there are two different chlorine atoms present and this can be understood by drawing the structure which is as shown below,
\[Cl-Ca-O-Cl\]
Here, one chlorine atom exists independently as attached to the central atom and the other is bound to the oxygen atom and therefore, there are two different oxidation states for these chlorine atoms.
- The oxidation state of chlorine atom that is directly attached to the central atom is -1 and the oxidation state of the chlorine atom attached to the oxygen atom therefore can be written as,
\[C{{a}^{2+}}{{(OCl)}^{-}}C{{l}^{-}}\]
Here, the oxidation state is -2 and correspondingly the oxygen state of chlorine here will become+1 and therefore it has +1 oxidation state.
So, the correct answer is “Option 2”.

Note: Note that bleaching powder is a basic compound which when reacted with acid particularly hydrochloric acid, it gives calcium chloride, chlorine and water and since the compound is not highly soluble in water, it smells strongly of chlorine.