BR Physics Electrostatics Examples

[Natnow]

Hello,

I would like to confirm the answer and explanation to a couple of BR Physics examples that I do no have the answers to.

8.1b When NaCl dissociates in pure H2O, the net charge of the electrolytic solution:
A. becomes negative
B. becomes positive
C. becomes neutral
D. becomes positive of negative, depending upon the relative Na+ and Cl- concentrations.

I am between A and C. I thought that electrolytic solutions have a charge. However with equal concentrations of Na+ and Cl- ions I would think the solution would be neutral. Could someone explain and maybe reiterate the definition of an electrolytic solution, for clarification?

Thank you so much for all your help!

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[jrhuynh94]

I would pick C because, to me, an electrolytic solution simply contains ions and is conductive.

 

[Natnow]

Thank you!
Another example:
8.2b A potassium ion and a chlorine ion are separated be a membrane, yet they exert an attractive force F on each other. When the membrane is three times thicker, the attractive force is F'. What is the ratio of F to F'?
A. 9:1
B. 3:1
C. 1:3
D. 1:9

The attractive force is going to be a lot stronger when the ions are closer to each other so that eliminates choices C and D. And since the distance is squared I would choose A. Do you agree?

Thanks y'all!

 

[jrhuynh94]

Coulomb's Law: F=Qq/r^2. If r is triple then the F=Qq/9r^2. Force decreases by a factor of 9, so yes.

 

[jrhuynh94]

F=kQq/r^2*