How does ion size affect conductivity?

1 Answer
Apr 7, 2014

In general, smaller ions have greater conductivity than larger ions.


Small ions have small areas. There is less resistance as they move through the solution.

For example, in molten salts, the conductivity of #"Li"^+# is greater than that of #"Cs"^+#.

Small ions have high charge density.

In aqueous solutions, this gives them a large hydration shell that moves with them.

For example, hydrated #"Li"^+# ions are larger than hydrated #"Cs"^+# ions.

Thus, aqueous solutions of lithium salts have lower conductivities than those of cesium.