Explain electrochemical series or electromotive series.

1.	Explain electrochemical series or electromotive series.
Answer» The conventions used in the construction of electrochemical series (or electromotive series) are as follows : The (reduction) electrodes or half cells of the elements are written on the left hand side of the series and they are arranged in the decreasing order of their standard reduction potentials (E°red). Reduction half reactions are written for each half cell in such a way that the species with higher oxidation state and electrons are on left hand side while reduced species with lower oxidation state are on right hand side. The standard reduction potential of standard hydrogen electrode is 0.00 V, i.e., \(E^0_{H^+/H_2}\) = 0.0 V. The electrodes and half cell reactions with positive E⁰_red values are located above hydrogen and those with negative E⁰_red values below hydrogen. Above hydrogen, positive E⁰_red values increase, while below hydrogen negative E⁰ values increase. The positive E⁰_red values indicate the tendency for reduction and the negative E⁰_red values indicate the tendency for oxidation. The elements, whose electrodes are at the top of the series having high positive values for E⁰_redare good oxidising agents. The elements, whose electrodes are at the bottom of the series having high negative values for E⁰_red are good reducing agents.

Answer»

The conventions used in the construction of electrochemical series (or electromotive series) are as follows :

The (reduction) electrodes or half cells of the elements are written on the left hand side of the series and they are arranged in the decreasing order of their standard reduction potentials (E°red).
Reduction half reactions are written for each half cell in such a way that the species with higher oxidation state and electrons are on left hand side while reduced species with lower oxidation state are on right hand side.
The standard reduction potential of standard hydrogen electrode is 0.00 V, i.e., \(E^0_{H^+/H_2}\) = 0.0 V. The electrodes and half cell reactions with positive E⁰_red values are located above hydrogen and those with negative E⁰_red values below hydrogen. Above hydrogen, positive E⁰_red values increase, while below hydrogen negative E⁰ values increase.
The positive E⁰_red values indicate the tendency for reduction and the negative E⁰_red values indicate the tendency for oxidation.
The elements, whose electrodes are at the top of the series having high positive values for E⁰_redare good oxidising agents.
The elements, whose electrodes are at the bottom of the series having high negative values for E⁰_red are good reducing agents.

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