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Question: In the reaction, \(Fe{S_2} + KMn{O_4} + {H^ + } \to F{e^{3 + }} + S{O_2} + M{n^{2 + }} + {H_2}O\) , ...

In the reaction, FeS2+KMnO4+H+→Fe3++SO2+Mn2++H2OFe{S_2} + KMn{O_4} + {H^ + } \to F{e^{3 + }} + S{O_2} + M{n^{2 + }} + {H_2}O , the equivalent mass of FeS2Fe{S_2} would be equal to \\_\\_\\_\\_\\_\\_\\_
A: Molar mass
B:Molar Mass10\dfrac{{{\text{Molar Mass}}}}{{10}}
C: Molar Mass11\dfrac{{{\text{Molar Mass}}}}{{11}}
D: Molar Mass13\dfrac{{{\text{Molar Mass}}}}{{13}}

Explanation

Solution

Equivalent mass is the mass of 11 equivalent which is equal to Molar MassValency\dfrac{{{\text{Molar Mass}}}}{{{\text{Valency}}}} .Valency is the charge on an atom if the molecule was ionic. It can be replaced by oxidation number or change of oxidation number.
Formula used: Equivalent Mass=Molar MassValency{\text{Equivalent Mass}} = \dfrac{{{\text{Molar Mass}}}}{{{\text{Valency}}}}.

Complete step by step answer:
FeS2+KMnO4+H+→Fe3++SO2+Mn2++H2OFe{S_2} + KMn{O_4} + {H^ + }\xrightarrow{{}}F{e^{3 + }} + S{O_2} + M{n^{2 + }} + {H_2}O
Oxidation state of FeFe in FeS2Fe{S_2} is +2 + 2
Oxidation state of SS in FeS2Fe{S_2} is −1 - 1
Oxidation state of FeFe after reaction takes place is +3 + 3
Oxidation state of SS in SO2S{O_2} is +4 + 4
Fe2+→Fe3++e−F{e^{2 + }}\xrightarrow{{}}F{e^{3 + }} + {e^ - }
Number of electron lost is 11
S−1→S+4+5e−{S^{ - 1}}\xrightarrow{{}}{S^{ + 4}} + 5{e^ - }
Number of electron lost is 55 but in reaction 22 sulphur atoms are present therefore total electron loss will be 1010
1 molecule of FeS2Fe{S_2} lost total 10+1=1110 + 1 = 11 electrons therefore change in oxidation number is 1111 as we know that
Equivalent Mass=Molar MassValency{\text{Equivalent Mass}} = \dfrac{{{\text{Molar Mass}}}}{{{\text{Valency}}}}
=Molar Mass11= \dfrac{{{\text{Molar Mass}}}}{{11}}
Therefore the answer to this question is option C that is Molar Mass11\dfrac{{{\text{Molar Mass}}}}{{11}}.

Additional information: Redox reaction is a type of chemical reaction in which the oxidation states of atoms are changed. Redox reactions are characterized by transfer of electrons between chemical species in which 11 species undergoes oxidation and others undergo reduction. Chemical species from which electrons are removed are said to have been oxidized; on the other hand species which gain electrons are said to have been reduced. In other words we can say that oxidation is loss of electron and reduction is gain of electron. During the combustion of wood with molecular oxygen, the oxidation state of carbon atoms in wood increases and that of oxygen atoms decreases as carbon dioxide CO2C{O_2} and water H2O{H_2}O are formed this means oxygen undergoes reduction and carbon undergoes oxidation. Also we can say that oxygen is an oxidizing agent and carbon is a reducing agent in this case. Oxidizing agents are the species which itself undergoes a reduction but oxidizes others similarly reducing agents are the species which itself undergoes oxidation and reduces others.

Note:
Equivalent mass is also called gram equivalent.
Don’t get confused with oxidizing and reducing agents. Oxidizing agent itself undergoes reduction and reducing agent itself undergoes oxidation.