ELECTRO CHEMISTRY
UNIT – I
ELECTRO CHEMISTRY
Definition:
“Electro chemistry is the branch of physical chemistry which deals with the transformation of electrical energy to chemical energy and vice-versa.”
It has a two coverage, firstly with the nature and the properties of substances containing ions and charged particles and secondly with the relationship between electrical currents and chemical reaction.
Electrical conductor:
“These are those substances which allow passage of electricity. Most metals are generally good conductors of electricity while non-metals are generally non-conductors of electricity.
Types of electrical conductors:
These are of two types
1. Metallic conductors
2. Electrolyte conductors
Metallic conductors:
“These are those conductors which allow the passage of electricity through them with out making any chemical change.
Ex: copper wire.
Electrolyte conductors:
“These are those conductors which allow the passage of electricity through them with chemical change occurring due to electrolysis.
Ex: salt(NaCl, KCl), Acids(HCl), Bases(NaOH).
Electrolytes are of two types :
a. Strong Electrolyte
b. Weak Electrolyte
Strong Electrolyte:
These are those electrolytes which ionize very rapidly.
Ex: HCl, NH4Cl
Weak Electrolyte:
These are those electrolytes which ionizes little.
Ex: NH4OH, CH3COOH
Electrolyte in solution: (Electrolysis)
“The Process of decomposition of electrolyte in its molten state or solution phase by passing electricity is known as electrolysis.”
Some typical changes caused by flow of electrons through two of the electrolyte under different condition is discussed as follows.
Electrolysis of Molten NaCl:
NaCl melts at 8010C to give a colorless clear liquid melt. When two inert electrodes like graphite are dipped in to this melt and connected to a source of direct current the following changes takes place.
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