In an extraction how would you know which layer is organic and which layer is aqueous?

Question

If you dont know the relative densities????

Answer 1

Take a pasteur pipette and add a drop of water.

If the aqueous layer is on the bottom, your drop of water will sink through the top layer and increase the volume of the bottom layer. If the aqueous layer is on top, the top layer will increase in volume.

The volume change will be most obvious in a separatory funnel.

In general, though, only halogenated solvents will be more dense than water. Pretty much all non-water soluble solvents, including hydrocarbons(hexanes, heptanes etc), heavy alcohols(n-butyl and larger), and ethers will be less dense than water.

Answer 2

As a general rule the aqueous layer is the lower -more dense- heavier layer. Sodium Carbonate should dissolve in this layer. It may also react to remove any acid by 'fizzing' - release of CO2.
The oily layer is the upper - less dense - lighter layer.

Answer 3

you don't

most organics are lighter than water and will reside on top

but solvents like methylene chloride is denser and will be the bottom layer