Explain molar conductance and electrochemical cell

Electrochemical Cells

The chemical changes which involve the flow of electric current are called electrochemical changes.

These are broadly of two types:

1) Electrochemical cells or Galvanic cells

These constitute the electrochemical reactions in which chemical energy is converted to electrical energy. In these cells, spontaneous redox reaction is used to generate an electric current.

The devices in which chemical energy of a spontaneous redox reaction is converted into electrical energy are called electrochemical cells or galvanic cells. In these devices, the Gibbs energy of the spontaneous redox reaction is converted into electrical work which may be used for running a motor or other electrical gadgets like heater, fan, geyser, etc.

An early example of a galvanic cell is a Daniel cell which was invented by the British chemist John Daniel in 1836. Daniel cell was constructed on the basis of the following spontaneous redox reaction :

Zn (s) + Cu²⁺ (aq) ⇔ Zn²⁺ (aq) + Cu (s)

Molar conductivity

Molar conductivity of a solution at a given concentration is the conductance of volume V of a solution containing one mole of electrolyte kept between two electrodes with an area of cross-section A and distance of unit length.

Ʌ_m = К/c

Here,

c = concentration in moles per volume
К = specific conductivity
Ʌ_m = molar conductivity.