Page:Outlines of Physical Chemistry - 1899.djvu/223

 KOHLBAtJSCH'S LAW

��conductivity of such a solution is 119*3 (Kohlrausch units), then half of this number, namely, 59*7, expresses the con- ductivity coefficient of potassium and also of chlorine.

We are now in possession of the key to the system. For, if from the conductivity of the solution of sodium chloride (1 equivalent in 1,000 litres) we subtract the co- efficient for chlorine we find the value 41*1 for sodium. By similar deductions the value 32*4 has been found for lithium* and values have also been found for many more

The coefficients thus deduced stand in the same ratio to each other as do Hittorfs values for the rates of migration deduced from the changes of concentration at the elec- trodes. Thus the one method confirms the results obtained by the other.

The study of neutral salts in aqueous solution thus gives us, for a series of monovalent ions, the factor known as the coefficient of conductivity or often as the speed of migration.

Acids of the type HC1 and HN0 3 have very high con- ductivities, mostly due to the high speed of the hydrogen ion, as the following shows :

��1 The majority of the numbers here cited are taken from Ostwald's book. They have been determined by Kohlrausch and refer to the temperature 18°C. and to dilutions 1,000 to 2,000 litres. — At this same temperature, but at infinite dilution, Kohlrausch has calculated the following conductivity co-efficients : Na u = 4X

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