Question
Define electrochemical series and write its two applications.
✓
Answer
EMF series is defined as the arrangement of the electrode with the electrode half$-$reaction in order of decreasing standard potentials.
$1.$ Oxidizing and Reducing Strengths: The electrochemical series helps to identify the substances that are good oxidizing agents and reducing agents. All the substances appearing on the top of the series behave as good reducing agents. All the substances appearing at the bottom of the table are good oxidizing agents.
$2.$ Displacement reactions: A metal higher in the series will displace the metal from its solution which is lower in the series. A metal higher in the series has a greater tendency to provide electrons to the cations of the metal to be precipitated. The metal having low standard reduction potential will displace the metal from its salt's solution which has a higher value of standard reduction potential.
$3.$ Predicting the Liberation of Hydrogen Gas from Acids by Metals: All metals having negative electrode potentials $(- E^\circ )$ show a greater tendency of losing electrons as compared to hydrogen. So, when such a metal is placed in an acid solution, the metal gets oxidized, and $H^+$ ions get reduced to form hydrogen gas. Thus, the metals having $- E^\circ$ values liberate hydrogen from acids.
$4.$ Predicting the Feasibility of a Redox Reaction: Depending on the $E^\circ$ values of the two electrodes feasibility of the given redox reaction can be found out. A redox reaction is feasible only if the species which has higher potential is reduced i.e., accepts the electrons and the species which has lower reduction potential is oxidized i.e., loses electrons.
$5.$ Calculation of the EMF of the Cell: If the $\text{EMF}$ of the cell is positive, the reaction is feasible in the given direction and the cell is correctly represented. If it is negative, the cell reaction is not feasible in the given direction and the cell is wrongly represented.
$6.$ Comparison of Reactivities of Metals: The relative ease with which the various species of metals and ions may be oxidized or reduced is indicated by the reduction of potential values. The metals with lower reduction potential are not reduced easily but are easily oxidized to their ions losing electrons.
$1.$ Oxidizing and Reducing Strengths: The electrochemical series helps to identify the substances that are good oxidizing agents and reducing agents. All the substances appearing on the top of the series behave as good reducing agents. All the substances appearing at the bottom of the table are good oxidizing agents.
$2.$ Displacement reactions: A metal higher in the series will displace the metal from its solution which is lower in the series. A metal higher in the series has a greater tendency to provide electrons to the cations of the metal to be precipitated. The metal having low standard reduction potential will displace the metal from its salt's solution which has a higher value of standard reduction potential.
$3.$ Predicting the Liberation of Hydrogen Gas from Acids by Metals: All metals having negative electrode potentials $(- E^\circ )$ show a greater tendency of losing electrons as compared to hydrogen. So, when such a metal is placed in an acid solution, the metal gets oxidized, and $H^+$ ions get reduced to form hydrogen gas. Thus, the metals having $- E^\circ$ values liberate hydrogen from acids.
$4.$ Predicting the Feasibility of a Redox Reaction: Depending on the $E^\circ$ values of the two electrodes feasibility of the given redox reaction can be found out. A redox reaction is feasible only if the species which has higher potential is reduced i.e., accepts the electrons and the species which has lower reduction potential is oxidized i.e., loses electrons.
$5.$ Calculation of the EMF of the Cell: If the $\text{EMF}$ of the cell is positive, the reaction is feasible in the given direction and the cell is correctly represented. If it is negative, the cell reaction is not feasible in the given direction and the cell is wrongly represented.
$6.$ Comparison of Reactivities of Metals: The relative ease with which the various species of metals and ions may be oxidized or reduced is indicated by the reduction of potential values. The metals with lower reduction potential are not reduced easily but are easily oxidized to their ions losing electrons.
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