The effect of concentration on equivalent conductance can be studied from the plots of λC values versus square root of concentration of the electrolyte. By doing so, it has been found that different types of plots are obtained depending on the nature of electrolyte.

**VARIATION
OF EQUIVALENT CONDUCTANCE WITH CONCENTRATION**

The effect of concentration on equivalent
conductance can be studied from the plots of λ_{C} values versus square root of concentration of
the electrolyte. By doing so, it has been found that different types of plots
are obtained depending on the nature of electrolyte. For strong electrolytes l_{C} decreases linearly
with increase in sq.root _{C} while for weak electrolytes, there is a
curve type of non linear decrease of l_{C} with sq.root_{ C} .

For strong
electrolytes Debye, Huckel and Onsager equation can be applied.

λ_{C} = λ_{¥} - (A + B λ_{¥} ) sq-rt _{C} to the linear plot of l_{C} versus sq.rt (_{C }) for strong electrolytes, the intercept value equals to λ_{¥} value which is obtained by extrapolating the line to 'y' axis ( _{C}
= 0). The slope value equals to (A + B λ_{¥}). A and B
are called as Debye constants for strong electrolytes.

In case of weak electrolytes, degree of
dissociation (a) increases when concentration decreases. Hence,
(1 - a) value tends to zero at infinite dilution, such that λ_{C} increases and tends
to λ_{¥} value.

λ_{¥} of weak electrolytes are experimentally obtained by extrapolating the upper arm of the curve to the Y axis and the intercept value
corresponds to λ_{¥}. In the intermediate concentration range, λ_{C} is lower than λ_{¥} since the weak electrolyte exists in partially ionised state. The
degree of dissociation a equals to the ratio of λ_{C} to λ_{¥} value.
(i.e., a = λ_{C} / λ_{¥}).

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