This type of cells becomes dead over a period of time and the chemical reaction stops. They cannot be revitalized or used again. Some ordinary examples are dry cell, mercury cell, etc.

    
Dry cell: it is a compact form of Leelanche cell known after its discoverer. In this cell, anode consists of zinc container while cathode  is a graphite rod surrounded by powdered MnO₂ and carbon. The space between the electrodes is filled with the paste of NH₄Cl and ZnCl₂. The arrangement is shown in the reaction taking place at the electrodes are given in their simplified from as follows:

Cathode:

MnO₂ + NH₄⁺ + e^-     MnO(OH) + NH3

(Oxidization state of Mn changes from + 4 to + 3)

Anode:

Zn    Zn²⁺ + 2e^-

The zinc ions (Zn²⁺) so produced combine with ammonis liberated zinc (II) cation.

Zn²⁺ + 2NH₃     [Zn(NH₃)₂]²⁺

Dry cells do not have long life as NH₄Cl which is acidic, corrodes the zinc container even if the cell is not in use. The cell potential of dry cells lies in the range 1.25 V to 1.5 V.

Mercury cell: it is miniature cell which finds a frequent use these days to supply energy for watches, video cameras, hearing aids and other compact devices. In mercury cell the anode is zinc-mercury and amalgam and the cathode is a paste of mercury (II) oxide and carbon electrolyte is a moist paste of KOH-ZnO. 

The operating voltage for mercury cell is 1.35 V and the cell reactions are as follows:

 

Such a cell shows constancy in its potential throughout its life.

 

 

 

 

 

 

Posted Date: 6/26/2012 2:07:05 AM | Location : United States

Ask an Expert

Related Discussions:- What are primary cells and explain its reactions?, Assignment Help, Ask Question on What are primary cells and explain its reactions?, Get Answer, Expert's Help, What are primary cells and explain its reactions? Discussions

Write discussion on What are primary cells and explain its reactions?
Your posts are moderated

Write your message here..

Related Questions

Determine the architectural units of silicates, Determine the architectural... Determine the architectural units of silicates This common architectural unit (SiO 4 4- ) of silicates is of remarkable stability. The different silicates may be classified

Intercoversion of alcohol, explain the chemical change that take place in t... explain the chemical change that take place in the conversion primary alcohols into secondary alcohols

Synthesis of proteins - functions of nucleic acid, Synthesis of proteins : ... Synthesis of proteins : The DNA consists of the genetic code and directs protein synthesis by RNA. The two helix of DNA partly uncoils and approximately the individual strands

Lanthanides, properties of lanthanides properties of lanthanides

Emperical and molecular formula, A hydrocarbon is burnt completely in exces... A hydrocarbon is burnt completely in excess oxygen.it is found that 5.0g of the hydrocarbon gives 14.6g carbon dioxide and 9.0g of water.knowing that relative molecular mass of the

Draw the structural formulas of both isomeric free acids, In solid state ch... In solid state chemistry the CN 2 2- ion shows constitutional isomerism. The free acids of both anions (at least in the gas phase) are known. Illustrate the structural formul

Help with Worksheet, Given "X" could be any element determine the charge on... Given "X" could be any element determine the charge on ''X'' given the following chemical formula: X3P

Metallurgy, methods for metallurgy methods for metallurgy

What is tracers?, In the study of mechanisms of various chemical reactions,... In the study of mechanisms of various chemical reactions, Deuterium and Tritium are used as tracers.

Determine the concentration of hydroxide ion in this buffer, In lab, buffer... In lab, buffers solution based onto a 0.1 M solution of sodium phosphate at pH7.0.  Within this system, there are three of pK A s like:  12.7, 7.21 and 2.12. Determine the conce