Question

Identify Z in the reaction given below:
$2MnO_{4}^{-}+5{{H}_{2}}{{O}_{2}}+6{{H}^{+}}\to 2Z+5{{O}_{2}}+8{{H}_{2}}O$
A. $M{{n}^{2+}}$
B. $M{{n}^{4+}}$
C. $Mn$
D. $Mn{{O}_{2}}$

Answer 1

Hint: To find the product we need to analyse the given reaction and find out that the given parts are getting reduced or oxidized. If the given part is getting oxidized, we can conclude that the species to be identified is a reduced product and it will have oxidation number less than that of the metal in the reactant.

Complete answer:
Reduction is the process of gain of electrons during a reaction by a molecule, atom or ion. It occurs when the oxidation state of a molecule, atom or ion is decreased. The process opposite to this is called oxidation, which occurs when there takes place a loss of electrons or the oxidation state of a species increases. If we consider the reaction given below, we see that, ${{H}_{2}}{{O}_{2}}$ is oxidized to ${{O}_{2}}$. Hence, the metal should get reduced to the lower stable oxidation state.

$2{{H}_{2}}{{O}_{2}}\to {{O}_{2}}+2{{H}_{2}}O$

Also, by balancing the charge we can conclude that the reaction taking place is:
$2Mn{{O}_{4}}+5{{H}_{2}}{{O}_{2}}+6{{H}^{+}}\to 2M{{n}^{2+}}+5{{O}_{2}}+8{{H}_{2}}O$

Here, from this reaction we can infer that the hydrogen peroxide reduces to an acidic medium.
Thus Z is $M{{n}^{2+}}$.
Hence, option A is correct which is $M{{n}^{2+}}$ ion.

Note: A redox reaction can be defined as a chemical reaction in which electrons are transferred between the two reactants participating in it. This transfer of electrons can be identified by observing the changes taking place in the oxidation states of the reacting species.