1.

Define the terms given below : (a) Conductivity (b) Molar conductivity What are their units ?

Answer»

Solution :(a) Conductivity (K) : Conductivity of a material in `S m^(-1)` is its conductance when it is 1 m long and its AREA of cross-section is `1 m^(2)`? The conductivity has the SI units as `SM^(-1)`? but quite often k is expressed in S `cm^(-1)`?.
`1 S cm^(-1) = 100 S m^(-1)`
(b) Molar conductivity (`Lambda_(m)`): Molar conductivity of a solution at a given concentration is the conductance of the volume V of the solution containing one mole of electrolyte kept between two electrodes with area of cross-section A and distance of unit LENGTH.
`Lambda_(m) = (KA)/l`
Since, l =1 and A =V, we have
`Lambda_(m) = kV`
The units of molar conductance are `S cm^(2) MOL^(-1)`.


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