Assume that during an extraction experiment you have lost track of which layer is the aqueous layer. How could you determine which layer is which by the use of a simple test?
you got it right in the search. Organic Chem
The shape of the miniscus is often a good way to tell.
Could you elaborate Dr Russ?
The aqueous phase has a concave meniscus. The majority of organic phases have a convex or flat meniscus. Thus by looking at the interface between the two phases it is often easy to decide which is which. With experience you can tell by letting a little out of the bottom of the separating funnel in to the tube below the tap. The aqueous phase tends to form a drop which stays put while an organic phase immediately runs out of the tube.
If the two phases are in a separating funnel then drop a little of the phases on to a waxed/greased surface. The aqueous phase forms blobs while the organic phase tends to spread out.
To determine which layer is the aqueous layer in an extraction experiment, you can follow a simple test called the salt-water test. Here's how you can do it:
1. Prepare a small amount of a saturated salt solution by dissolving table salt (sodium chloride) in water. The solution should be concentrated enough to make a noticeable difference in density.
2. Take a small sample of one of the layers (let's call it Layer A) with a clean dropper or pipette and transfer it to a separate test tube or container.
3. Add a few drops of the saturated salt solution to the test tube containing Layer A.
4. Gently mix or shake the test tube to allow the layers to separate again.
5. Observe the separation of layers. If the added salt solution causes the layer to become more dense and sink to the bottom, then Layer A is the aqueous layer. If there is no change or the layer floats on top, then it is not the aqueous layer.
6. Repeat the same process with the other layer (Layer B). Add a few drops of the saturated salt solution to the test tube containing Layer B and observe the separation.
By performing the salt-water test on both layers, you will be able to determine which layer is the aqueous layer based on the change in density caused by the added salt solution. The layer that becomes more dense and sinks to the bottom after adding the salt solution is the aqueous layer.