Question
Question: Oxidation number of \('CO'\) in \(Hg\left[ Co{{\left( SCN \right)}_{4}} \right]\) A) \(+2\) B)...
Oxidation number of ′CO′ in Hg[Co(SCN)4]
A) +2
B) +1
C) +3
D) +5
Solution
Oxidation is defined as the loss of electrons during a reaction. When oxidation takes place it results in the increase in the oxidation state. Reduction is defined as the gain of electrons during a reaction. During reduction, decrease in oxidation state takes place.
Complete step-by-step answer:
Oxidation number can be defined as when ionic bonds are formed with other heteroatoms, a charge is formed on that atom. If an atom has high electronegativity then it shows negative oxidation state. It always forms ionic bonds by gaining or losing electrons.
As we know that atoms have multiple valence electrons and they form multiple bonds with all the atoms. They are considered as ionic and the oxidation state is equal to the number of electrons involved during bonding. The ionization energy will be high when the atom contains a larger charge and becomes difficult to remove an electron.
To calculate the oxidation number of atom, we need to follow these steps-
-First we will add up the constant oxidation state of an atom.
-After that, we will equate the total oxidation state of a molecule to the total charge of the molecule.
-Constant oxidation state means that the net charge of the ion is equal to the oxidation state of charged ions. For alkali metal ions, it is always equal to +1 .For alkali earth metal, it is always equal to +2 and so on.
In this question, the oxidation state of Hg is +2 which is a stable state and therefore it leaves a −2 charge in the coordination sphere.
We should know the oxidation state of SCN is −1
Let us take the oxidation state of Co be x
Now, the coordination complex in the question given is –
Hg[Co(SCN)4]
Now , to calculate oxidation number, we should know the formula to calculate oxidation number
(Co)×1+(SCN)×4=−2
Here, (CO) is the oxidation state that is x
(SCN) is the oxidation state of SCN
−2 is the total charge in coordination sphere
Now, substituting the value in the above formula we get
⇒x×1+4(−1)=−2
⇒x−4=−2
On further solving we get
x=+2
Therefore, the oxidation number of CO is +2
Hence, the option A is the correct answer.
Note: In a homonuclear diatomic molecule, the oxidation number of the atom is equal to zero. For example- hydrogen, oxygen, nitrogen. Oxidation numbers are the integers that can be positive, negative or zero.