Why can't hexane or toluene solutions dissolve in aqueous bromine?

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Discussion Overview

The discussion revolves around the solubility behavior of hexane and toluene in aqueous bromine, particularly in the context of a lab experiment where distinct layers were observed after mixing. Participants explore the polar and non-polar nature of the substances involved and the implications for solubility.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes an experiment where hexane and aqueous bromine did not mix, leading to the observation of two distinct layers, which they attribute to the principle of "like dissolves like."
  • Another participant explains that aqueous bromine is a solution of bromine in water, suggesting that the non-polar nature of hexane and toluene prevents them from mixing with the polar aqueous solution.
  • A different participant questions the previous explanation, proposing that bromine in the aqueous solution exists in an ionic state, which could account for the lack of solubility in hexane or toluene.
  • Another participant challenges the ionic state claim by pointing out that the solution appeared red, implying the presence of Br2 rather than an ionic form.

Areas of Agreement / Disagreement

Participants express differing views on the nature of bromine in the aqueous solution and its implications for solubility, indicating that multiple competing explanations remain unresolved.

Contextual Notes

There are unresolved questions regarding the state of bromine in the aqueous solution and the definitions of polar and non-polar in this context, which may affect interpretations of the experimental results.

redpower
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I have just carried out a lab experiment today and desperately need some help!

1. The Experiment:

In my experiement I attempted to mix a solution of hexane with aqueous bromine. I started off by adding 15 drops of bromine into a test tube and then added 7 drops of hexane ontop of that. Prior to shaking, I could see two distinct colours in the test tube separated by a meniscous: the yellow bromine liquid lied at the bottom and the clear + colourless hexane solution lied on top of the bromine. After shaking, something odd happened. The two layers switched places => bromine ended up on top and hexane resided at the bottom of the test tube. The two colours were still distinct and separated by a meniscous. (The same thing happened when I tried to mix toluene with bromine)


2. What I discovered

Seeing that these two solutions would not dissolve each other, I concluded that one of them must be polar and the other must be non-polar. (We have previously learned that only "like dissolves like") HOWEVER, after analysing the substances, I realized that hexane (a hydrocarbon) and bromine are BOTH NON-POLAR SUBSTANCES. If that is the case, they should have dissolved each other - but they didn't! Thus, I am in a dilemma right now and have no idea how to approach this lab.

Any help would be greatly appreciated! Thank you in advance!
 
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Aqueous bromine is bromine dissolved in a water based solution. Usually HBr and H20. Your bromine preparation did not mix with either hexane or toluene because of their non-polar nature. They are non-miscible with water. Gaseous bromine, either Br2(g) or HBr(g), would dissolve however.
 
MrCoffee2004 said:
Aqueous bromine is bromine dissolved in a water based solution. Usually HBr and H20.

HBr in bromine solution? Some amount being produced in disproportionation - for sure, but this is not the main form of Br2 present.
 
I don't think that is right. If it were, the Br2 would have dissolved into the hexane or toluene. The Br was in an ionic state in the aqueous solution and that is why it didn't dissolve.
 
If it was ionic, how come solution was red?
 

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