Thread: Conductivity of solutions

Hi

Can someone please explain why a solution will conduct electricity better than an other? Specifically regarding NaCl and KI. Iam sure this is a simple concept but I just can't seem to get my head around it!! I understand basically the process of conductivity, but not why one of these solutions would conduct better than the other one?

Thanks for anyone's help, it's greatly appreciated!!!

Originally Posted by helphelp

Hi

Can someone please explain why a solution will conduct electricity better than an other? Specifically regarding NaCl and KI. Iam sure this is a simple concept but I just can't seem to get my head around it!! I understand basically the process of conductivity, but not why one of these solutions would conduct better than the other one?

Thanks for anyone's help, it's greatly appreciated!!!

I'm rusty on this so open to correction from others, but I think it is because conduction in an electrolyte depends on the rate of diffusion of the ions carrying the current. Different ions move at different speeds - and the comparative speeds may not be as one might first think, since the effective size of a solvated ion, and hence its ease of motion, depends on the envelope of solvent molecules and ions of the opposite polarity that are either strongly or weaker associated with it as it moves. For example I understand that Na+ diffuses more slowly than K+ in aqueous solution, due to its tendency to attract a bigger crowd of followers than K+ does. There's a table of conductivity values for some ions in this Wiki link, in the section on Strong Electrolytes: Conductivity (electrolytic) - Wikipedia, the free encyclopedia

Originally Posted by PhDemon

The short answer is it's due to the ionic size and mobility of the ions in solution, larger ions move through the solution more slowly and hence conduct charge less efficiently. This effect is complicated in aqueous solution by the size of the solvation shell around the ion so the charge density as well as the absolute size has to be taken into consideration.

The link below explains this in more detail:

http://mystudyexpress.com/12 th scie...pdf file/6.pdf

Curses, you beat me to it by 2 minutes.