Question

The spontaneous cell reaction (i.e., redox reaction) in a galvanic cell is derived by :
(A) reduction reaction at the right electrode - reduction reaction at the left electrode
(B) oxidation reaction at left electrode + reduction reaction at right electrode
(C) reduction reaction at right electrode + reduction reaction at left electrode
(D) oxidation reaction at left electrode - oxidation reaction at right electrode

Answer 1

Hint: The Galvanic cell is one which consists of two electrodes, one called the anode and the other cathode in two compartments which perform two half cell reactions- the oxidation reaction and the reduction reaction. The EMF of a cell can be given as-
EMF = $E_{SRP,cathode}^0 + E_{SOP,anode}^0$

Complete step by step answer:
Let us start by knowing what a galvanic cell is.
The Galvanic cell is also called a voltaic cell. It is an electrochemical cell which derives its electrical energy from the spontaneous redox reactions that occur in the cell.
Now, what is a spontaneous redox reaction? The sword spontaneous means the thing occurring at a particular moment. And the redox means involving the oxidation and reduction of of both reactions.
The redox reaction is defined as the one in which in one chemical reaction, the reduction and oxidation of both the processes are taking place.
The redox reaction can be broken into the oxidation half-reaction and the reduction half-reaction.
In a galvanic cell, the oxidation half-reaction and reduction half-reaction; both occur in separate compartments which are connected by an external electrical circuits.
There is a flow of ions from one compartment to the other.
The oxidation in the Galvanic cell occurs at the anode which is the left electrode while the reduction occurs at the cathode which is the right electrode.
We know that EMF of a cell can be given as-
EMF = $E_{SRP,cathode}^0 + E_{SOP,anode}^0$
This means, EMF = reduction at cathode + oxidation at the anode.
We know that anode is the left hand side electrode and the cathode is the right hand side electrode.
Thus, EMF = reduction at right electrode + oxidation at left electrode.
This is the option (B)

So, the option (B) could be the answer.

Further, we have another relationship.
EMF = $E_{SRP,cathode}^0 - E_{SRP,anode}^0$
This means, EMF = reduction at cathode - reduction at the anode.
Thus, EMF = reduction at the right electrode - reduction at the left electrode.
This is the option (A).

So, the option (A) is the correct answer.

Now, one more relation is
EMF = $E_{SOP,anode}^0 - E_{SOP,cathode}^0$
This means EMF = oxidation at anode - oxidation at the cathode.
Thus, EMF = oxidation at left electrode - oxidation at right electrode.
This is the option (D).

So, the option (D) is the correct answer.

The option c.) is the addition of reduction of both the electrodes. This can not be the correct answer.

So, we have the correct answer: option (A), option (B) and option (D).

Note: The two compartments in two half cells are joined which allow the free movement of the electrons in compartments. The spontaneous reaction does not require any energy from outside for the reaction to occur. Such a reaction gives out energy which can be used to perform work.