# NCERT Solutions, CBSE Sample paper, Latest Syllabus, NCERT Books, Last Year Question Papers and Many More ...

## Question 7:Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.

Question 7:Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.

Conductivity :–
Conductivity of a solution is equal to the conductance of a solution of 1 cm length and cross section area of 1 square cm.  it may also be define as the conductance of ine centimeter cube of the conductor . It is represented by the symbol Kappa (κ). mathematically we can write
κ = 1/ p
here ρ is resistivity
the unit of K is ohm –1 cm –1 or S cm–1
The conductivity, κ, of an electrolytic solution depends on the concentration of the electrolyte, nature of solvent and temperature.

Molar conductivity:
Molar conductivity of a solution at a given concentration is the conductance of the volume V of solution containing one mole of electrolyte kept between two electrodes with area of cross section A and distance of unit length. Therefore,
Distance is unit  so l = 1
Volume       = area of base × length
So V = A × 1  = A
Λm      =κA/l
Λm      = κV
Or
Molar conductivity increases with decrease in concentration. When concentration approaches zero, the molar conductivity is known as limiting molar conductivity and is represented by the symbol Ë°m.
For strong electrolytes, Λ increases slowly with dilution and can be represented by the equation:
Λm = Ë°m° – A c ½

It can be seen that if we plot Λm against c1/2, we obtain a straight line with intercept equal to Ëm° and slope equal to ‘–A’. The value of the constant ‘A’ for a given solvent and temperature depends on the type of electrolyte i.e., the charges on the cation and anion produced on the dissociation of the electrolyte in solution.

Open your video in VLC player or add '.mp4' extension at end of the video

Define conductivity, Define molar conductivity, Discuss variation with concentration