Question

The standard ${{E}^{\circ }}$ values of few redox couples are $Z{{n}^{2+}}/Zn = -0.76V,A{{g}^{+}}/Ag=+0.08V,C{{u}^{2+}}/Cu = 0.34V$ Choose the correct option?
(A) Ag can oxidise Zn and Cu
(B) Ag can reduce $Z{{n}^{2+}}$ and $C{{u}^{2+}}$
(C) Zn can reduce $A{{g}^{+}}$ and $C{{u}^{2+}}$
(D) Cu can reduce $Z{{n}^{2+}}$ and $A{{g}^{+}}$

Answer 1

In this question, we have been given ${{E}^{\circ }}$ values of few redox couples, $Z{{n}^{2+}}/Zn = -0.76V, A{{g}^{+}}/Ag = +0.08V, C{{u}^{2+}}/Cu = 0.34V$ we need to choose the correct option on the basis of these values. So, for that, we will refer to the reactivity series to find out which is the most reactive element out of these. And as we know Zn being more reactive than Cu and Ag will easily be able to reduce $A{{g}^{+}}$ and $C{{u}^{2+}}$.

Complete step by step answer:
- We have been provided with the ${{E}^{\circ }}$ values or the standard reduction electrode potential of few redox couples,
- We know that the SREP or standard reduction electrode potential of an element determines its tendency to gain electrons or to get reduced.
- Also, $Z{{n}^{2+}}/Zn = -0.76V,A{{g}^{+}}/Ag = +0.08V,C{{u}^{2+}}/Cu = 0.34V$ out of these elements,
If we refer to the reactivity series, we know that Zn is the most reactive metal out of these three,
The order of reactivity would be: $Zn>Cu>Ag$,
- Now as their SREP values are also given and according to them the order would get reversed.
- So, from the above information, copper has the maximum tendency to get reduced, followed by Ag and Zn respectively.
- So, Zn will oxidize to $Z{{n}^{2+}}$ and $C{{u}^{2+}}$ will be reduced to Cu, by the application of Ag.
- So, Cu can oxidise both $Z{{n}^{2+}}$ and $A{{g}^{+}}$.
So, the correct answer is “Option D”.

Note: In this question we have been provided with SREP so, don't get confused as SREP and SOEP are different. The standard oxidation potential measures the tendency for a given chemical species to be oxidized as opposed to being reduced. Standard reduction potential is measured using a galvanic cell that contains a SHE on one side and an unknown chemical half cell on the other side.