Looking for classes? Ksquare Career Institute, Bengaluru →
Electrochemical series
Appears in
Concepts tested here
- Feasibility of a redox reaction
- Oxidising and reducing agents
- Reducing power
All Questions
2012 AIPMT-MAINS 1 question
-
Standard reduction potentials of the half reactions are given below:
$F_2(g) + 2e^- \rightarrow 2F^-(aq)$; $E^0 = +2.85$ V
$Cl_2(g) + 2e^- \rightarrow 2Cl^-(aq)$; $E^0 = +1.36$ V
$Br_2(l) + 2e^- \rightarrow 2Br^-(aq)$; $E^0 = +1.06$ V
$I_2(s) + 2e^- \rightarrow 2I^-(aq)$; $E^0 = +0.53$ V
The strongest oxidising and reducing agents respectively are:A higher reduction potential means a greater tendency to be reduced, i.e. a stronger oxidising agent.
$F_2$ has the highest $E^0$ (+2.85 V), so it is the strongest oxidising agent.
The $I_2/I^-$ couple has the lowest $E^0$ (+0.53 V), so $I^-$ is most easily oxidised and is the strongest reducing agent.
2011 AIPMT-MAINS 1 question
-
A solution contains $Fe^{2+}$, $Fe^{3+}$ and $I^-$ ions. This solution was treated with iodine at $35^\circ C$. $E^\circ$ for $Fe^{3+}/Fe^{2+}$ is +0.77 V and $E^\circ$ for $I_2/2I^-$ = 0.536 V. The favourable redox reaction isThe couple with the higher standard reduction potential undergoes reduction and the other undergoes oxidation.
$E^\circ(Fe^{3+}/Fe^{2+}) = +0.77$ V is greater than $E^\circ(I_2/I^-) = +0.536$ V, so $Fe^{3+}$ is the stronger oxidising agent.
Reduction: $2Fe^{3+} + 2e^- \rightarrow 2Fe^{2+}$; oxidation: $2I^- \rightarrow I_2 + 2e^-$
Overall: $2Fe^{3+} + 2I^- \rightarrow 2Fe^{2+} + I_2$
$E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode} = 0.77 - 0.536 = +0.234$ V
$E^\circ_{cell}$ is positive, so this reaction is spontaneous; the reverse (oxidation of $Fe^{2+}$ by $I_2$) is not.
Hence $I^-$ will be oxidised to $I_2$.
2011 AIPMT-PRE 1 question
-
Standard electrode potentials of three metals X, Y and Z are −1.2 V, +0.5 V and −3.0 V respectively. The reducing power of these metals will beA reducing agent is itself oxidised. The lower (more negative) the standard reduction potential of a metal, the more easily it is oxidised and the stronger it is as a reducing agent.
Reduction potentials: Z = −3.0 V, X = −1.2 V, Y = +0.5 V.
Increasing order of reduction potential: Z < X < Y.
Reducing power is the reverse of this order.
Hence the reducing power is Z > X > Y.