can you plz explain the functioning of daniell cell when and external voltage opposing the cell potential is applied.

Asked by Jinu sony | 20th Oct, 2013, 11:08: AM

Expert Answer:

This cell converts the chemical energy liberated during the redox reaction in to electrical energy and has an electrical potential equal to 1.1V when concentration of Zn2+ and cu2+ions is unity (1molar).

Zn(s) +  Cu2+(aq)   ?   Zn2+(aq)  +  Cu(s)

This reaction is a combination of two half reaction whose addition gives the overall cell reaction.

The reduction half reaction occurs on the copper electrode so that copper electrode may be called the reduction half cell.

Cu2+  +   2e  ?   ?  Cu(s)

Oxidation half reaction occurs on the zinc electrode so that zinc electrode may be called the oxidation half cell

Zn(s)  ?   Zn2   +   2e  ?

The electrolytes of the two half - cells are connected internally through a salt bridge. Sometimes, both the electrodes dip in the same electrolyte solution and in such cases we do not require a salt bridge.

In this device the Gibbs energy of the spontaneous redox reaction is converted into electrical work which may be used for running motor or other electrical gadgets like heater, fan, geyser etc.

 

Answered by Hanisha Vyas | 25th Oct, 2013, 11:04: AM

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