What would the best way to determine the organic layer from the aqueous layer in a extraction procedure?
~would it be to add a few drops of water to each layer and see what happens? or is there a better way since this procedure of adding a few drops of water to the extraction vial would introduce water into the organic layer and then the water would thus have to be removed and thus would defeat the whole purpose of seperating the layers in the first place.
Thanks =D
The easiest way is to look up the densities of the organic layer and water. But you already know the density of water as 1.00 (at least close enough). The organic layer will be on top if it is less dense and on bottom if it is more dense.
The reason I ask is b/c the book says to not necessarily trust the book b/c If you have another compound dissolved in it which makes it denser than the water it can go on the bottom or be reversed.
I can actually look up the info but the density of the compounds aren't in the Merck Index (or I can't find them)(I bought it new 14th edition and it came with a cd too).
If they are in a sep funnel, you have no choice except to pull the bottom layer off first, then the top layer next. After they are in two separate containers, adding some organic solvent to both will tell you (using organic solvent instead of water gets around the objection in the original question), the odor should tell you, etc.
What solvents?
Um I have to use a pasteur pipette to get the bottom layer off from the solution in the conical vial.
I guess I could add some after seperating them since the instructions are to evaporate the solvent anyways.
That's a good I idea to add the organic solvent instead of water to the individual separated solutions.
Thanks Dr.Bob =D
solvents?
Methylene chloride
n-butyl chloride
n-butyl bromide
saturated aqueous sodium bromide
the last 3 are just to let us determine which is a organic layer when mixed with water, I also have to determine which is the organic layer when the 2 last ones are mixed too.
I have to make the table of chemicals in my lab book before lab and I looked at the Merck Index but either it wasn't in there or I don't know how to read the notation but I'm thinking it's the latter.
Thanks Dr.Bob
From The Merck Index---
methylene chloride density = 1.33 g/cc
n-butyl chloride = 0.89 g/cc
n-butyl bromide = 1.27 g/cc
so I expect you are reading it. Were they not listed. Go to the index FIRST (don't try to look them up by name in the alphabetical listing because they may be known by several name) since the index will list them several ways and they are crossreferenced so if you look up dichloromethane it will say "see #??" and go to that number and it is listed as methylene chloride.
An aqueous solution of NaBr COULD be as dense as n-butyl bromide but my gut feelihng is it ins't. Anyway, you will have n-butyl bromide there and you will have the saturated solution of NaBr there, so in a small test tube, add the two and see which floats.
for methylene chloride...
it was listed as
d415 1.33479
but here was a d-4-0 before this and after this there was a d-4-20 and a d-4-30 and after that there was something noted as n-D-20...
Which should I use ?? the one listed as d-4-15 all the time?
(I'll analyze the rest after I go and eat so I'm not done with this but I wanted to go and list what I saw for the methylene chloride first)
the nD20 is the refractive index at 20o. The n is refractive index, the D is using the D lines of sodium (spectroscopic lines of 589.0 nm and 589.6 nm) for the light source and 20 is T.
d is density. The notation of d420 = xx means the density of the substance at 20o C referred to water at 4o C.