A2 Physics Experiment: Electrical Conductance Through Salt Solution

[Anastasya]

After summer I have to do my physics A2 experiment coursework. I really like working with electricity and looking at what happens at an atomic level, but I fear that what I want too do is more chemistry than physics.

I had the idea of look at electrical conductance through a salt solution. I would begin with distilled water and gradually add salt (of a specific type), and see what happens to the conductance as the salt concentration increases. On top of this I would look at the effect of changing conductance on temperature. in both cases I want to look at a relationships (graph it etc) and why this happens on an atomic level.

Is this experiment more to do with chemistry and physics though? Or can I do it as my A2 physics experiment?

any comments, guidance, suggestions would be great.

Anya

 

[rude man]

It's both, I guess. But looking at it from a physics view:

When you add salt you can assume the salt is entirely dissolved and the NaCl molecules split into Na+ and Cl- ions, each with a charge of 1e. Then knowing the amount of salt dissolved you can get the number of free ions per unit volume of solvent, then compute conductivity based on a comparison with a metal, say Cu, with known free electron density. Should be interesting! In the case of the salt solution remember there are positive as well as negative charges floating around... also that you start depleting ions and manufacturing deadly Chlorine gas! So I would take my data very quickly then shut off the current!

 

[Anastasya]

thank you so much for replying,I really appreciate it. I shall write up the experiment plan, focusing on the physics side as you mentioned and present to my teacher and see what he thinks.

and thanks so much for for mentioning the latter 'deadly chlorine gas' part, it slipped my mind. if I do end up preforming this experiment I most definitely will take my data quickly and turn of the current ASAP!

thanks again.