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

Inorganic salt analysis of greenish white, which kind Acid &Basic radical p... which kind Acid &Basic radical present in this?

Calculate the mean heat capacity, a) Calculate the energy required to heat ... a) Calculate the energy required to heat 1kg of CO 2 from 400 o C to 600 o C at a constant pressure of 1atm using:- i) The mean heat capacity data given below ii) The heat c

How many atoms does Gold have? , Gold has a molar mass of 197g/mol. How man... Gold has a molar mass of 197g/mol. How many atoms are in the sample?Please give me procedure also. Ans) molecular wieght of gold is 197 g 1mole/g of molecule is occupies t

Describe about groups or families in periodic table, Q. Describe about grou... Q. Describe about groups or families in periodic table? Every element may be represented by a one or two letter symbol. In the middle of nineteenth century a Russian chemist Dm

Difference between thermoplastic and thermosetting polymers, Difference bet... Difference between thermoplastic and thermosetting polymers Thermoplastic polymers Thermosetting polymers (1) Thermoplastic polymers

Fiehes test, sir plz tell me about fiehes test procedure for honey in detai... sir plz tell me about fiehes test procedure for honey in detail...

Dithizone, can -COOH group be attached with the phenyl group of dithizone? can -COOH group be attached with the phenyl group of dithizone?

Hydrogyn, does hydrogyn react with magnesium does hydrogyn react with magnesium

Bohr''s principle the relation between principle quantum no, According to B... According to Bohr's principle, the relation between principle quantum number and radius of orbit is: (1) r ∞ n    (2) r ∞ n 2       (3) ∞1/n  (4) r∞ 1/ n 2 Ans:  r

Buffers, how do you prepare 100mM pH 7.4 of Potassium phospate buffer how do you prepare 100mM pH 7.4 of Potassium phospate buffer