Respuesta :
Answer :
a. The oxidizing agent is: [tex]BH_4^-[/tex]
b. The reducing agent is: [tex]ClO_3^-[/tex]
Explanation :
Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.
Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.
Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.
Reducing agent : It is defined as the agent which helps the other substance to reduce and itself gets oxidized. Thus, it will undergo oxidation reaction.
Oxidizing agent : It is defined as the agent which helps the other substance to oxidize and itself gets reduced. Thus, it will undergo reduction reaction.
The given chemical reaction is,
[tex]BH_4^-(aq)+ClO_3^-(aq)\rightarrow H_2BO_3^-(aq)+Cl^-(aq)[/tex]
The oxidation-reduction half reaction will be :
Oxidation : [tex]BH_4^-\rightarrow H_2BO_3^-[/tex]
Reduction : [tex]ClO_3^-\rightarrow Cl^-[/tex]
Now balance oxygen atom on both side.
Oxidation : [tex]BH_4^-\rightarrow H_2BO_3^-+3H_2O[/tex]
Reduction : [tex]ClO_3^-+3H_2O\rightarrow Cl^-[/tex]
Now balance hydrogen atom on both side.
Oxidation : [tex]BH_4^-+4OH^-\rightarrow H_2BO_3^-+3H_2O[/tex]
Reduction : [tex]ClO_3^-+3H_2O\rightarrow Cl^-+6OH^-[/tex]
Now balance the charge.
Oxidation : [tex]BH_4^-+4OH^-\rightarrow H_2BO_3^-+3H_2O+4e^-[/tex]
Reduction : [tex]ClO_3^-+3H_2O+6e^-\rightarrow Cl^-+6OH^-[/tex]
In order to balance the electrons, we multiply the oxidation reaction by 6 and reduction reaction by 4 and then added both equation, we get the balanced redox reaction.
Oxidation : [tex]6BH_4^-+24OH^-\rightarrow 6H_2BO_3^-+18H_2O+24e^-[/tex]
Reduction : [tex]4ClO_3^-+12H_2O+24e^-\rightarrow 4Cl^-+24OH^-[/tex]
The balanced chemical equation in acidic medium will be,
[tex]6BH_4^-+4ClO_3^-\rightarrow 6H_2BO_3^-+6H_2O+4Cl^-[/tex]
[tex]3BH_4^-+2ClO_3^-\rightarrow 3H_2BO_3^-+3H_2O+2Cl^-[/tex]
In the redox reaction, [tex]ClO_3^-[/tex] act as oxidizing agent and [tex]BH_4^-[/tex] act as an reducing agent.
