Decrease in temperature of an aqueous salt solution decreases conductivity

Why does the conductivity of a water solution drop as the temperature decreases?

How are these two related?

• I'm in the middle of understanding the relation since it's a question made by my professor at the university. There is no data to compare yet although I would be glad to provide a much more detailed question to help others who may read this. Feb 3 '19 at 17:28
• I've asked a follow-up question: Is there an electronic component to water conductivity?
– uhoh
Feb 4 '19 at 0:42

In the SED theory the frictional drag coefficient $$f$$ of a charged particle is proportional to the viscosity $$\eta$$: $$f \propto \eta$$ As a result the electrical mobility $$\mu$$ of an ion of charge $$q$$ is inversely proportional to the viscosity, since $$\mu =q/f\propto \eta^{-1}$$ and since the specific conductance $$\kappa$$ depends linearly on the mobilities (approximately, at constant ionic strength), $$\kappa \propto \eta^{-1}$$ Since the viscosity usually increases with decreasing temperature, the conductivity decreases.