Consider these two entries from a fictional table of standard reduction potentials?

standard-reduction

#1

Consider these two entries from a fictional table of standard reduction potentials.

X2+ + 2e- => X(s) E=1.70 V
Y2+ + 2e- => Y(s) E=0.14 V

Which pair of species would react under standard conditions?

_X2 and Y
_X2 and Y2
_X and Y
_X and Y2

Concepts and reason
Gibbs free energy of the overall reaction is negative, then the reaction is said to be spontaneous.
From the two half-cell reactions, we can find standard cell potential.
The relation between standard cell potential and Gibbs free energy is as follows:
image

From the relation imageis positive then Gibbs free energy is negative. Then that reaction is spontaneous.
And, from the relation image is negative then Gibbs free energy is positive. Then that reaction is non-spontaneous.
Reactive species which in a galvanic cell, the oxidation reaction takes place at anode and the reduction reaction takes place at cathode. The standard potential (image) can be calculated using the following formula:
image

Fundamentals
In the two given half cells, one of the half-cell reaction undergo oxidation and other half-cell reaction is reduction.
The reaction which is having, more positive standard reduction potential that reaction undergo reduction and other reaction which is having less positive reduction potential undergo oxidation reaction.
In galvanic cell oxidation reaction takes place at anode and reduction reaction takes place at cathode.

The standard potential image can be calculated using the following formula:
image
The relation between standard cell potential and Gibbs free energy is as follows:
image

Answer:

The standard reduction potentials for the two half-reactions are as follows:
image

Explanation:
The ion which has higher reduction potential undergoes reduction and the other ion or atom undergoes oxidation.

The oxidation half-reaction is as follows:
At anode: image
The reduction half-reaction is as follows:
At cathode: image
Now, calculate the standard potential for this galvanic cell as follows:
image
Therefore, the value of image is + 1.56 V.
The relation between standard cell potential and Gibbs free energy is as follows:
image
From the relation image is positive then Gibbs free energy is negative. Then that reaction is spontaneous.
Therefore, the pair of species would react under standard conditions are species image

image

Explanation:
The species undergo reaction at standard conditions, the standard cell potential value imagewill be positive. Then the corresponding species have negative Gibbs free energy.