Question

To study molar conductivity of 1,2,3,4,5 M solution of NaCl .
Explain all briefly

Answer 1

Answer:

Molar conductivity of a solution at a given concentration is the conductance of volume V of a solution containing 1 mole the electrolyte kept between two electrodes with the area of cross-section A and distance of unit length.

Λ  

m

​  

=k  

l

A

​  

 

Now, l=1 and A=V (volume containing 1 mole of the electrolyte).

∴Λ  

m

​  

=kV  

Molar conductivity increase with a decrease in concentration. This is because of the total volume V of the solution containing mole of the electrolyte increases on dilution.

Variation of molar conductivities with dilution:

For strong electrolytes, molar conductivity slowly increases with dilution.

For weak electrolytes, molar conductivity increases steeply on dilution, especially near lower concentrations.

The variation of Λ  

m

​  

 with  

c

​  

 for strong and weak electrolytes are shown in the following plot: (ref. image)

(b) Given,

conductivity, σ=0.146×10  

−3

Scm  

−1

 

Resistance, R=1500Ω

∴ Cell constant =σ×R

=0.146×10  

−3

×1500

=0.219cm  

−1