[makode101]

Hi there, this question is for high school chemistry grade 12. The unit we're working on now is studying bonding and structure properties. We conducted various experiments and in this particular experiment I mixed:
- iodine with water, hexane, and ethanol
- graphite with water, hexane, and ethanol
- Calcium Chloride (CaCl₂) with water, hexane, and ethanol
and we had to test the conductivity of each solution (after mixing). The results yielded are:

+           Water       Hexane       Ethanol
Iodine   103 mV   11 mV   0.3 mV
Graphite   109 mV   83 mV   0.4 mV
CaCl2           207 mV      84 mV     2 mV
(mV = millivolts)

I tried to come up with a good explanation for any of the above but I keep getting stuck.
I know that iodine and water don't mix, and that water is polar and iodine isn't, so when the current is run through the water, the I₂ molecules would hinder the current and therefore lower the voltage? Is that the correct way to approach this?
Again, with the graphite, that doesn't mix with the water, and it is "bigger" than the iodine, so why would it yield a higher voltage than iodine+water?
My final question for now is, how come ethanol has such lower conductivity than hexane even though ethanol is partially polar and hexane is completely non-polar?
This whole thing is giving me a headache 
Any help would be appreciated!
- Omar

[Mitch]

Why do you think CaCl₂ worked the best?

[makode101]

Well I know CaCl₂ is ionic and that would definitely help the current go through. I'm just having a hard time visualizing the whole process, so the electrons come in.. then what? How does having CaCl₂ in the water change the voltage vs. not having it in there?
I researched a lot on google and forums but haven't found anything.

[Borek]

You are interested in conductivity, but you measured voltage?

[makode101]

It was actually the teacher who conducted that experiment and we're expected to answer the question which is:
Explain the results obtained for conductivity based on particle types in the solution.
and the results she gave us were in mV

[DevaDevil]

Borek is right: conductivity is measured in Siemens, not Volt

in fact, the Volt isn't even a potential drop due to solution resistance, as then the higher Voltage drop would indicate the higher resistance (and such is not the case in your experiment)

[makode101]

Well thanks anyway guys, I figured out my results were actually in correct, the ethanol and hexane were switched by accident so it makes more sense now

[Mitch]

 

[vmelkon]

I know that iodine and water don't mix, and that water is polar and iodine isn't, so when the current is run through the water, the I2 molecules would hinder the current and therefore lower the voltage?

So you are saying iodine and water don't mix and also
iodine and water mix and causes hindrance.