Question

I need help completing this flowchart on separating a mixture of sand, sodium chloride, and acetanilide

Answer 1

The key to most "how do I separate." questions is solubility.

The trick is to add a liquid that will only dissolve one substance but not another.

Let's say you had a beaker full of sand, table salt (NaCl), and acetanilide. Is there anything you can add that would only dissolve one of these three substances?

Yes, there is! Acetanilide like most organic compounds, isn't soluble in water. But salt is soluble in water. So to the mixture, I would add water, and then pass the water through a filter. The filter paper will "catch" the sand and acetanilide, but the table salt will remain dissolved in the water. If you then let that water evaporate (either via boiling or under vacuum), you will recover your salt.

So now, how to do you separate the sand from the acetanilide? Sand isn't really soluble in anything, but acetanilide is soluble in organic solvents, such as ethanol. So to the mixture of sand and acetanilide, add ethanol, and pass it through a filter. The sand will once again get stuck in the filter paper, and your acetanilide will be dissolved in ethanol. Remove the ethanol (via vacuum, or rotovap) and you will be left with acetanilide.