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Question: How do electrochemical cells produce voltage?...

How do electrochemical cells produce voltage?

Explanation

Solution

We know that an electrochemical cell is a device that is capable of producing current due to the chemical reaction taking place in the cell. There are two kinds of electrochemical cell namely voltaic cell and electrolytic cell.

Complete step by step answer:
Let’s understand how electrochemical cells produce voltage. We take the spontaneous reaction of Zn in copper sulphate solution.
Oxidation reaction:
Zn(s)→Zn(aq)+2e−{\text{Zn}}\left( s \right) \to {\text{Zn}}\left( {aq} \right) + 2{e^ - }
Reduction reaction:
Cu2 + (aq)+2e−→Cu(s){\text{C}}{{\text{u}}^{{\text{2 + }}}}\left( {aq} \right) + 2{e^ - } \to {\text{Cu}}\left( s \right)
The reaction is,
Zn(s) + Cu2 + (aq)→Zn(aq)+Cu(s){\text{Zn}}\left( s \right){\text{ + C}}{{\text{u}}^{{\text{2 + }}}}\left( {aq} \right) \to {\text{Zn}}\left( {aq} \right) + {\text{Cu}}\left( s \right)
So, when both reactants (zinc and copper ion) are placed together, zinc transfers its electron directly to copper ions. The zinc ions go to solution and the deposition of copper takes place in the surface of zinc. So, in this process we will not be able to get the useful energy from this reaction.
But there is a way to obtain energy from the same reaction by setting an electrochemical cell to separate the oxidation and reduction reaction.
In an electrochemical cell, zinc passes electrons to the copper ion by an external wire. The tendency of the system to go to a lower energy state results in voltage difference between the electrodes.

Additional Information:
Let’s discuss two types of electrochemical cells.
Voltaic cell: In this cell, the conversion of chemical energy of spontaneous reaction into electrical energy takes place. This type of cell is used in radio, cell phones etc.
Electrolytic cell: In this type of cell, there is a need for electrical energy to carry out spontaneous reactions.

Note: It is to be remembered that electrochemistry is a branch to study the production of electricity from the spontaneous chemical reaction. Metals such as sodium, magnesium can be produced by the electrochemical process.