) is called the specific conductance (or) conductivity. It is represented by the symbol κ appa ( ) κ . Substitute in equation ( . ) and rearranging = C ρ κ κ ⇒ .
A l .....( . ) If A = 1m and = 1m l ; then κ = C. The specific conductance is defined as the conductance of a cube of an electrolytic solution of unit dimensions(Fig . ).
The SI unit of specific conductance is Sm - . Example A conductivity cell has two platinum electrodes separated by a distance . cm and the cross sectional area of each electrode is . sq cm.
Using this cell, the resistance of . N Unit of = . A ohm . m m ohm m = mho m - - κ κ R l - (or) Sm Fig .
conductivity of a cube of an electrolytic solution 1m 1m 1m Electrolytic Solution XII U9 Electro XII U9 Electro - - - - electrolytic solution was measured as Ω . Find the specific conductance of the solution. Solution κ = R A l l = . cm = .
m m m - κ Ω A = . cm m = . Sm - ( R = Ω . .
Molar conductivity ( m Λ Solutions of different concentrations have different number of electrolytic ions in a given volume of solution and hence they have different specific conductance. Therefore a new quantity called molar conductance ( m Λ was introduced. Let us imagine a conductivity cell in which the electrodes are separated by 1m and having V m of electrolytic solution which contains mole of electrolyte. The conductance of such a system is called the molar conductance ( m Λ We have just learnt that the conductance of m electrolytic solution is called the specific conductance ( ) κ .
Therefore, the conductance of the above mentioned V m solution ( m Λ is given by the following expression. ( ) = V m Λ κ × .....( . ) We know that, molarity (M) = Number of moles of solute (n) Volume of the solution (V in dm ) Therefore, Volume of the solution containing one mole of solute = M mol L -