Conductanceis the flow of electricity. The measurementof conductanceis done in terms of resistance. It is denoted by G. So conductance isa measure of with which current flows through the conductor. It isdefined as reciprocal of resistance. The resistance is denoted by R.The conductor resistance is directly proportional to the length ofconductor (l) and inversely proportional to the cross section area ofconductor (a).
So the R α l/a, R="ρ" l/a, where ρ is the proportionality constant and known asspecific resistance or resistivity.
Thus the conductance G="1/R." The unit of G is ohm-1.Ohm is the unit of resistance. It is also expressed in terms ofSiemens or S. 1 S = 1 ohm-1.We can also say that conductivity is the measurement of concentrationof ions. It is increased with increasing the concentrations of ions.
The conductivity ofelectrolyte depends upon various factors. In aqueous solution, theelectrolyte splits into its ions. These are free to move in solution.This free movement of ions is responsible for conductance. So theconductance depends upon nature of electrolyte, size of ions,solvation nature, nature of solvent, viscosity of solvent,concentration of solution, and the last factor temperature.
Thus Specificconductance definitioncan be stated by the definition of conductance. This is denoted by κ(kappa). It is also reciprocal of resistivity. It can be defined asthe conductance of one meter or centimeter cube of the conductor.
Thus the specificconductance κ (kappa) = 1/ ρ = 1/R (l/a)
The unit of specificconductivity is κ (kappa) = 1/ ohm-cm = ohm-1cm-1or S cm-1.It is very useful for measuring the total dissolved solidsconcentration of ions like calcium, magnesium, sodium, bicarbonate,chloride, sulphate, potassium etc. The specific conductance valuesare altered from system to system. The measurement of specificconductance watercan be the main criteria for measuring the specific conductivitylevel. Or it can be explained in terms of increasing the ionic level.This is known as ionization ability of electrolyte.
The conductivity ofmetallic conductor has a definite value at a given temperature. Soin electrolytic solution, the conductivity depends only ontemperature but also varies with the concentrations of solutions. Itis due to the presence of ions.
So molarconductancecan be defined as conductance of solution that is kept between theelectrodes which are kept at unit distance apart and having crosssectional area large enough to take sufficient volume of the solutionthat contain one mole of electrolyte. It is denoted by μ.So μ = k ×V. The unit of molar conductance is ohm-1 cm2 mol-1or S cm2 mol-1.