The lower layer is Bromoform, tribromomethane CHBr3 with the highest density (2.889 g/cm3), almost three times greater than of water.
Trick:
To simply find out if water is the lower or upper layer in a two-layer fluid system, you can
- add carefully one drop of water at the top of the liquid
- watch accurately the path of the falling drop and when it does 'dissolve'
Then:
- when going down through the upper layer, then it will 'dissolve' in the lower, you may conclude the upper layer is NOT water.
Or
- when 'dissolving' immediately in the upper layer then you'll conclude the upper layer is water.
