CBSE class 12th chemistry notes
Electrochemistry chapter detail notes
Electrochemistry deals with the study of chemical processes involving the transfer of electrons between electrodes and electrolytes. Key concepts include:
Redox Reactions: Electrochemical cells involve oxidation-reduction ...
Chemistry Notes for class 12 Chapter 3
Electrochemistry
Electrochemistry is that branch of chemistry which deals with the study of production of
electricity from energy released during spontaneous chemical reactions and the use of electrical
energy to bring about non-spontaneous chemical transformations.
Importance of Electrochemistry
1. Production of metals like Na, Mg. Ca and Al.
2. Electroplating.
3. Purification of metals.
4. Batteries and cells used in various instruments.
Conductors
Substances that allow electric current to pass through them are known as conductors.
Metallic Conductors or Electronic Conductors
Substances which allow the electric current to pass through them by the movement of electrons
are called metallic conductors, e.g.. metals.
Electrolytic Conductors or Electrolytes
Substances which allow the passage of electricity through their fused state or aqueous solution
and undergo chemical decomposition are called electrolytic conductors, e.g., aqueous solution
of acids. bases and salts.
Electrolytes are of two types:
1. Strong electrolytes The electrolytes that completely dissociate or ionise into ions are
called strong electrolytes. e.g., HCl, NaOH, K2SO4
2. Weak electrolytes The electrolytes that dissociate partially (ex < 1) are called weak
electrolytes, e.g., CH3COOH, H2CO3, NH4OHH2S, etc.
Electrochemical Cell and Electrolytic
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A cell of almost constant emf is called standard cell. The most common is Weston standard
cell.
Galvanic cell is also called voltaic cell.
General Representation of an Electrochemical Cell
Other features of the electrochemical cell are
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1. There is no evolution of heat.
2. The solution remains neutral on both sides.
3. The reaction and now of electrons stops after sometime.
Daniell Cell
An electrochemical cell of zinc and copper metals is known as Daniell cell. It is represented as
By convention cathode is represented on the RHS and anode on the LHS.
Function of salt bridge
1. It completes the circuit and allows the flow of current.
2. It maintains the electrical neutrality on both sides. Salt-bridge generally contains
solution of strong electrolyte such as KNO3, KCL etc. KCI is preferred because the
transport numbers of K+ and Cl-are almost same.
Transport number or Transference number The current flowing through an electrolytic
solution is carried by the ions. The fraction of the current carried by an ion is called its
transport number or transference number. Thus.
Transport number of cation. nc = (current carried by cation/total current)
Transport number of cation. na = (current carried by anion/total current)
Evidently nc + na = 1
Electrode Potential
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