cyclohexane (1 Viewer)

[9876543210]

why is it when bromine water is added to a testube filled with cyclohexane, the bromine water initially sets at the bottom but after a while, the bromine water settles on top of the cyclohexane?

 

[boris]

Because of the jews

 

[Pwnage101]

good Q 9876543210 ,

here's wat i learnt:

bromine water is Br2(aq) ie its bromine molecules dissolved in water
thus its denisty is just about that of water, approx = 1g/mL

now cyclohexane has a density of about 0.8 g/mL

so it makes sense once u add them both, since no reaction occurs, the less dense (cyclohexane) is up the top, and the more dense is down the bottom

ie the brown/yello colour is initially down the bottom

now, u would know that water (H2O) is a POLAR molecule and interacts strongly via hydrogen bonding

cyclohexane on the other hand is NON POLAR and intercats via dispersion forces only

now remember it is the Br2 (bromine) molecule that gives the water that colour

now Br2 is NON-POLAR (because it contains 2 atoms of same element, thus electrons pair is equally spaced, no permanent dipole)

so, wat happens is teh Br2 that is doissolved in the water (ie that makes up 'the bromine water') moves FROM the water and dissolves IN the cyclohexane, because both are non-polar and will interact via dispersion forces, so now the Br2 is dissolved in teh cyclohexane (remember from prelim 'like dissolves like)

thus the 'bromine water' doesnt move to the top; the bottom will remain water, but the bromine molecules will migrate to the top cyclohexane layer, which will turn yellow/brown

hope that helps, post any Q's if u dont understand!

PS most HSC chem students wouldnt know this or look into this, so its an excellent Q!

 

[9876543210]

i get it now!!!
thx alot, Pwnage101.
my teacher insisted on us researching to find out but i couldnt find the reason why that happened.
thx again!
=]