Question

C2H5OH(aq) + MnO− 4 (aq) → Mn2+(aq) + CH3COOH(aq) of acetic acid from ethanol by the action of permanganate ion in acidic solution, identify the reducing agent. 1. MnO− 4 2. CH3COOH 3. Mn2+ 4. C2H5OH 013 (part 2 of 2) 10.0 points Balance the equation by using oxidation and reduction half reactions. What is smallest possible integer coefficient of MnO− 4 in the combined balanced equation?

Answer 1

Ethanol
`(C_2H_5OH)` act as reducing agent.

The smallest possible integer coefficient of
`MnO_4^-` in the combined balanced equation is, 4

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,

`C_2H_5OH(aq)+MnO_4^-(aq)\rightarrow CH_3COOH(aq)+Mn^(2+)(aq)`

The oxidation-reduction half reaction will be :

Oxidation :
`C_2H_6O\rightarrow C_2H_4O_2`

Reduction :
`MnO_4^-\rightarrow Mn^(2+)`

• Now balance oxygen atom on both side.

Oxidation :
`C_2H_6O+H_2O\rightarrow C_2H_4O_2`

Reduction :
`MnO_4^-\rightarrow Mn^(2+)+4H_2O`

• Now balance hydrogen atom on both side.

Oxidation :
`C_2H_6O+H_2O\rightarrow C_2H_4O_2+4H^+`

Reduction :
`MnO_4^-+8H^+\rightarrow Mn^(2+)+4H_2O`

• Now balance the charge.

Oxidation :
`C_2H_6O+H_2O\rightarrow C_2H_4O_2+4H^++4e^-`

Reduction :
`MnO_4^-+8H^++5e^-\rightarrow Mn^(2+)+4H_2O`

In order to balance the electrons, we multiply the oxidation reaction by 5 and reduction reaction by 4 and then added both equation, we get the balanced redox reaction.

Oxidation :
`5C_2H_6O+5H_2O\rightarrow 5C_2H_4O_2+20H^++20e^-`

Reduction :
`4MnO_4^-+32H^++20e^-\rightarrow 4Mn^(2+)+16H_2O`

The balanced chemical equation in acidic medium will be,

`5C_2H_6O+4MnO_4^-+12H^+\rightarrow 5C_2H_4O_2+4Mn^(2+)+11H_2O`

In the redox reaction ethanol act as reducing agent and permanganate ion act as an oxidizing agent.