[icanwishcanti]

hi i'm new in here    i'm here because i need help   yikes.  cant think anymore.  the more i think, the more brain cells dies   ehehe.  jk.

in the extraction of an organic compd from a dilute aqueous solution, will the organic solvent form the upper or lower layer when each of the following solvents are used in an extraction.

a) chloroform - bottom
b) n-heptane - bottom
c) cyclohexane - bottom
d) methylene chloride - bottom

I'm not sure if this talking about with water, because if this is talking abt with water than all the solvents will be on the bottom and water will be on the top since water has density of 1.00g/cm³.  Am I right?  If not, please help me.

I have another question:  if you been hired by a food company to develop a method to prepare decaffeinated coffee, what simple procedure that you might use for this purpose?  

My answer: separatory funnel

is that right?

any help would be greatly appreciated.

thank you!

[mike]

In general chlorinated solvents will be on the bottom of the two layers, other organics will usually be on the top.

[icanwishcanti]

thank you, mike  

[mike]

No problem.

A good way to remember this is that chlorine is a relatively big and heavy atom, especially compared to water (H2O) so will sink.

Whereas other organic compounds are similar to oils which float on top of water, you may have notcied oil slicks on a wet road on top of the water, or oil spills in the sea that float. Also salad dressing in a bottle needs to be shaken because over time the oil will float onto top of the water.

[Yggdrasil]

You can also check the densities of your solvents in something like the Merck index or in an online resource such as http://chemfinder.cambridgesoft.com

When in doubt, you can always take a small aliquot of the top layer and add water to it.  If the water mixes in, it's the aqueous phase.  If the water doesn't mix, it's the organic phase.

[Mitch]

Or just add water and see which layer gets larger.

[mike]

Or just add water and see which layer gets larger.

Yes this is what I usually do too.