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Question: What will be the equivalent weight of \(KCl{O_3}\) in the following reaction? \(3KCl{O_3}\; + \;3{...

What will be the equivalent weight of KClO3KCl{O_3} in the following reaction?
3KClO3  +  3H2SO4      →    3KHSO4    +  HClO4  +  2ClO2    +  H2O3KCl{O_3}\; + \;3{H_2}S{O_{4\;\;}}\; \to \;\;3KHS{O_{4\;\;}} + \;HCl{O_4}\; + \;2Cl{O_2}\;\; + \;{{\text{H}}_2}{\text{O}}

Explanation

Solution

We are given a redox reaction so first we should learn what redox reaction is. A redox reaction is a chemical oxidation-reduction reaction in which reactant atoms undergo a change in their oxidation state. Redox is a short form of reduction-oxidation. All redox reactions can be divided into two processes: oxidation process and reduction process. We will study the change in oxidation state of each molecule to calculate the equivalent mass of a given molecule.

Complete answer:
We are calculating equivalent weight, we should know first what is equivalent weight of a molecule. Equivalent weight is the mass of one equivalent mass of a given molecule that will combine with or react with a fixed amount of another molecule.
Disproportionation reaction
Oxidation
ClO3−    →  ClO4−      +  2e−Cl{O_3}^{ - \;}\; \to \;Cl{O_4}^{ - \;\;}\; + \;2{{\text{e}}^ - }
Calculating the change in oxidation state of Chlorine in above reaction, the chlorine is going +5 + 5 oxidation state to +7 + 7 oxidation state so change in oxidation state is two. Equivalent weight in this reaction
Moxd  =  M2{{\text{M}}_{oxd}}\; = \dfrac{{\;{\text{M}}}}{2}
where M is the molar mass of KClO3KCl{O_3}
Reduction
  e−  +  ClO3−    →  ClO2\;{{\text{e}}^ - }\; + \;Cl{O_3}^{ - \;\;} \to \;Cl{O_2}
Calculating the change in oxidation state of Chlorine in above reaction, Chlorine changes its oxidation state from +5 + 5 to +4 + 4. Equivalent weight in this case
Mred  =M{{\text{M}}_{red}}\; = {\text{M}}
Total equivalent weight will be the sum of equivalent weights in oxidation and reduction
Meq  =M  +    M2{{\text{M}}_{eq}}\; = {\text{M}}\; + \;\dfrac{{\;{\text{M}}}}{2}
Substituting the value of Molar mass of KClO3KCl{O_3} we get,
Meq  =  183.825  gmol−{{\text{M}}_{eq}}\; = \;183.825\;gmo{l^ - }

Note:
Equivalent weight is also known as gram equivalent; it is calculated by dividing the molar mass of a molecule by its valence or oxidation number in our case. Chlorine is undergoing oxidation and reduction in the same reaction; this type of reaction is known as a disproportionation reaction.