Question

A density column was made with 3 mL of 1 M calcium chloride solution with a density of 1.1 g/mL, 3 ml of dyed distilled water with a density of 1.00 g/mL, and then 3 mL of ethanol with a density of 0.80 g/mL. The calcium chloride solution was poured first followed by the distilled water and then ethanol. Why was the calcium chloride solution poured into the density column first?

Answer 1

The Calcium Chloride has the higher value of density. When you mix two or more liquids and these liquids are inmiscible or don't dissolve each other, the liquid with the higher density will go in the bottom of the recipient, flask, vessel, etc. This is because it has the higher mass/volume density, so this liquid will weight more than the others, therefore it will go to the bottom first. For this reason and for the fact that in order to avoid that the salt get mixed with water or alcohol and even to avoid that the water and ethanol gets impurities, the salt is poured first.

Hope this helps