Kohlrausch's Law
At infinite dilution, the molar conductivity of an electrolyte is the sum of independent contributions from its cations and anions.
Formula / equation
Λ°m = ν₊λ°₊ + ν₋λ°₋
Unit
S·cm²/mol
In depth
Because each ion migrates independently once dilution removes interionic interference, ionic conductivities are additive and transferable between salts. The law provides the only practical route to the limiting molar conductivity of a weak electrolyte, which cannot be measured by extrapolation.
Examples in the real world
Obtaining Λ° for acetic acid by combining values for HCl, sodium acetate and NaCl.