how can you prove which of the two layers in extraction is the methylene chloride?

Answer 1

You can use the effect of the earth's gravity to help you decide. Look up the specific gravity or density of each layer in the extraction. The one with the higher specific gravity or density will be the one on the bottom.

For example, say you were doing an extraction between water and methylene chloride at 25 Celsius. At 25 Celsius, methylene chloride has a specific gravity of 1.318 whereas water has a specific gravity of 0.997. Thus methylene chloride will be on the bottom and water will be on top.

Now let's say you had an extraction of methylene chloride with a cesium formate solution. I am not certain but say the cesium formate solution has a specific gravity of around 2.3 at 25 Celsius. In this case the cesium formate solution would be on the bottom while the methylene chloride would be on top.

Answer 2

Look up the density. Denser layer to the bottom.