2. Consider the following solvent pairs. If mixed together, which pairs would form two layers? If they form two layers, which solvent would be on top? Find the densities for each of these solvents in the CRC Handbook. [6 mks]
a. hexanes and water
b. water and methylene chloride
c. hexanes and methylene chloride
d. methanol and hexanes
e. ethanol and water
f. acetone and toluene
Did you look up the densities? The one with the lowest density will float on top. But note that e is miscible in all proportions and you won't have two layers. Same for f. So you have two questions here. First is which pairs will NOT mix. Of those, the lower density will float.
To determine which solvent pairs would form two layers when mixed together and which solvent would be on top, you need to consider the relative densities of the solvents.
First, find the densities of each solvent in the CRC Handbook. Look up the densities for hexanes, water, methylene chloride, methanol, ethanol, acetone, and toluene.
Once you have the densities, compare the densities of the solvents in each pair.
a. Hexanes and water: Compare the density of hexanes with the density of water. If hexanes have a higher density than water, the hexanes would be on the bottom layer. If hexanes have a lower density than water, the water would be on the bottom layer.
b. Water and methylene chloride: Compare the density of water with the density of methylene chloride. Again, if methylene chloride has a higher density than water, the methylene chloride would be on the bottom layer. If it has a lower density, water would be on the bottom layer.
c. Hexanes and methylene chloride: Compare the density of hexanes with the density of methylene chloride. The solvent with the higher density will be on the bottom layer.
d. Methanol and hexanes: Compare the density of methanol with the density of hexanes to determine which solvent would be on the bottom layer.
e. Ethanol and water: Compare the density of ethanol with the density of water to determine which solvent would be on the bottom layer.
f. Acetone and toluene: Compare the density of acetone with the density of toluene to determine which solvent would be on the bottom layer.
By comparing the densities of the solvents in each pair, you can determine which pairs would form two layers and which solvent would be on top.