Conductivity is caused due to inorganic dissolved salts in a solution called electrolytes.
Electrolytic solutions obey Ohm’s Law.
E= IR
Where, E = Electromotive Force
I = Current (in ampere)
R = Resistance of cell (in Ohm)
Resistance depends on the dimension of the conductor.
R= ρ L/ A
Where, L = length
A = Cross-sectional area of the conductor
ρ= Specific resistance.(ohm-cm)
Specific conductance is a conductance offered by a 1cc solution of electrolyte.
Specific Conductance = 1/ ρ (ohm-cm-1) or (mho /cm)
Cations Anions
H+ HCO3-
Na+ CO3--
Ca++ OH-
Mg++ Cl-
K+ NO3-
Fe++ SOCl-
Mn++ PO4---
Al+++ F-
Ionic strength α 1/ resistance
Ionic strength α Conductance
Specific conductance = C/R = Cell Constant / Resistance.
Specific conductance of each ion will contribute for total conductance.
0.01N KCl, at 25°C = Specific conductance = 0.001418 siemens = 1/ ohm.cm
The conductivity of a solution is a measure of its ability to carry an electrical current and varies both with the number of ions and type of ions the electrolyte contains.
µ = ½ Σ Ci Zi2
Where, Ci = Molar Concentration of Ion
Zi = Charge on ion.
γ = 0.5 Z2 √µ / 1+ √µ where, γ = Activity coefficient.