A c ½ ( . ) It can be seen that if we plot (Fig. . ) L m against c / , we obtain a straight line with intercept equal to L ° m 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 the solution. Thus, NaCl, CaCl , MgSO are known as - , - and - electrolytes respectively. All electrolytes of a particular type have the same value for ‘ A ’. Fig.
. : Molar conductivity versus c½ for acetic acid (weak electrolyte) and potassium chloride (strong electrolyte) in aqueous solutions. The molar conductivity of KCl solutions at different concentrations at K are given below: c /mol L – LLLLL m /S cm mol – .000198 . .000309 .
.000521 . .000989 . Show that a plot between L m and c / is a straight line. Determine the values of L ° m and A for KCl.
Taking the square root of concentration we obtain: c / /(mol L – ) / LLLLL m /S cm mol – .01407 . .01758 . .02283 . .03145 .
A plot of L m ( y-axis) and c / ( x -axis) is shown in (Fig. . ). It can be seen that it is nearly a straight line.
From the intercept ( c / = ), we find that L ° m = . S cm mol – and A = – slope = . S cm mol – /(mol/L – ) / .