You are given a mixture of sulfur potassium nitrate and carbon and asked to separate the components so you end up with a pile of solid sulfur a pile of solid potassium nitrate a pile of solid carbon?

Answer 1

So, you have a pile of gunpowder and you want to separate it. Right?

Here's are some clues:

Saltpeter (potassium nitrate) is soluble in water. Sulfur and carbon are not.

Furthermore, sulfur is soluble in acetone but carbon is not. This assumes that you have pure carbon and not charcoal powder. Depending on the quality of the charcoal powder, it could be more or less soluble in different substances. But let's just take your teacher at his word: Carbon is carbon.

If there is enough differential in particle size you could sift the mixture through a screen but that doesn't guarantee you'll get ALL the carbon, sulfur or saltpeter out of the mix. If the particles are all the same size that won't work at all.

(OR)

here is a better phrased answer:

Answer: Gunpowder is a mixture of sulphur, charcoal and potassium nitrate (nitre). When water is added to the mixture potassium nitrate dissolves. The mixture is then filtered. The filtrate is potassium nitrate solution while the residue is a mixture of sulphur and charcoal. The filtrate is evaporated on a sand bath to obtain nitre back. When carbon disulphide is added to the residue, sulphur dissolves. When this mixture is filtered the filtrate is sulphur solution while the residue is charcoal. Leaving it open evaporates the sulphur solution. Carbon disulphide evaporates and sulphur crystals are left behind.