In chlorine water test, why does the organic layer assume colour but not the aqueous layer
Answers
because organic layer is miscible which will remain on top of the aqueous layer. therefore, the organic layer will develop color and the aqueous layer will become colorless.
supporting knowledge
1. Chlorine can usually be smelled when levels are between 0.02 and 3.4 ppm.
2. organic layer v/s aqueous layer
let's start with an example.
suppose that you have a test tube that contains two layers -- an aqueous layer and an organic layer, but that you don't know which layer is which (top or bottom). If you drip a drop of water into the test tube, one of two things will happen. Either:
1) The drop will immediately dissolve as soon as it hits the top layer of liquid. In that case, the top layer is your aqueous layer!
-or-
2) The drop will not dissolve when it hits the top layer of your test tube, but instead will probably sink as a droplet down through the top layer. When that drop reaches the lower layer, it should dissolve. That is because the top layer is the organic layer, and the lower layer is aqueous.
Most of the time your top layer will be organic, because most common organic solvents used for extractions are less dense than water. However, certain organic solvents (like dichloromethane) are heavier than water, and in that case would be the lower layer.