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| Electrochemical cell |
Electrochemical cell and its types
Electrochemical cell
The
device in which chemical energy is converted into electrical energy is called
electrochemical cell.
Explanation: in electrochemical cell two
electrodes are dipped in water that is electrolyte and current is produced by
redox reactions.
Types of electrochemical cell
There are two types of electrochemical
cell
- Electrolytic cell
- Galvanic cell
Electrolytic Cell
Electrolytic
Cell
The
type of electrochemical cell in which non spontaneous chemical reaction takes
place when electric current is passed through the solution is called
electrolytic cell.
Construction:
An
electrolytic cell consists of a solution of electrolyte containing two
electrodes dipped in it and also attached a source of current that is battery.
Working: In an electrolytic cell when
electricity is passed through the ions in a solution. The positive ions moved
toward negatively charged cathode where it take electrons and
Became reduced to form neutral atoms.
The negativity ions move towards positively charged anode where it lose or give
electrons and became oxidize to form through fused sodium chloride and
following reactions take place.
Oxidation at
anode
Reduction at
cathode
Uses of Electrolytic cell
It is use in
- Ion refining and purifying process
- In electroplating process as well.
Galvanic Cell or Voltaic cell or Daniel cell
Galvanic
Cell
The
type of electrochemical cell in which spontaneous chemical reaction takes place
and electric current is produced is called galvanic cell, voltaic cell or
Daniel cell.
Construction
The Daniel
cell which is the simple example of galvanic cell consists of two half cells. One
half cell is zinc rod dipped in one molar ZnSO4 solution and working
as anode. The other half cell is Copper rod dipped in molar solution of CuSO4
and working as cathode. These two half cells are connected by U shaped
salt bridge containing saturated solution of strong electrolytes. This u shaped
salt bridge is sealed by porous material. The function of this salt bridge is
to keep the solution of both cells neutral by providing the path of for
migration of ions.
Working
When both cells are
connected by metal wire that is volt meter. The cell starts producing electric
current. AS Zinc loses electrons more easily that copper therefore zinc undergoes
oxidation to form zinc ion by loss of electrons and go to ZnSO4 solution.
These electrons of zinc traveled through wire to copper electrode. These
electrons are accepts by copper and copper ion undergoes reduction and become
stable atom. In this solution zinc electrode dissolves in the solution and
reducing in size to transferring of electron to copper electrode and copper
electrode grew in size. During this process following reaction takes place.
Zn •••► Zn+2 + 2e
Cu+2 + 2e •••► Cu
