how do you separate a heterogeneous mixture of zinc powder, mercury, sulfur and iron?

Answer 1

If this is meant to be a practical question and not a theoretical one, then treat the mixture with Carbon disulfide. This will dissolve the solid Sulfur, but will not react with the metals. This step must be done in a hood or well ventilated area. Filter the mixture and the metals will be in the filter paper. Evaporate the Carbon disulfide in a closed system evaporator to get the solid Sulfur back. Although Benzene and Toluene will work, Sulfur is very much more soluble in Carbon disulfide.

Next, dry the metals and then remove the Iron using a magnetic field. Iron filings should be readily removed from the mixture. You will now have a mixture of Zinc and Mercury.

No matter how carefully you did the above steps, at least some of the Zinc will have formed an amalgam (alloy) with the Mercury. This will make the last step the most difficult. Treat the mixture with dilute Hydrochloric acid. Gently heat and agitate well. The Zinc (even the Zinc in the amalgam) will react with the acid liberating Hydrogen gas. Decant the liquid and wash with water. This will leave you with Mercury and an acidic solution of Zinc chloride.

The solid metallic Zinc can be regained by either adding an active metal (like Calcium) or by electroplating from the acidic solution.

Answer 2

1. use a magnet to pull out the iron
2. add HCl to react with the zinc. Pour off the solution of zinc chloride. If you want the zinc back, neutralise the HCl and add calcium metal.
3. add methylbenzene (toluene) and warm. This will dissolve the sulphur. Evaporate (in a fume cupboard) to get the sulphur back.
4. you should be left with just the mercury!

Answer 3

since you have mercury it will be quite difficult to completely separate the mixture as metals form amalgams with mercury.
ok now i just hope this works,
bubble oxygen through the mixture
S,Zn and Fe should react to form their respective oxides.
SO2 is a gas and will be displaced.
ZnO and Fe2O3 if and when formed can be removed by evaporation of the mercury.
then the iron and zinc oxides can be magnetically separated.

theoretically it should work but not sure so other posters please dont abuse me for this post.

Answer 4

If a magnet is hold near to the mixture ,the iron particles are attracted by the magnet and the remaining part of the mixture i.e,sulphur powder is separated

Answer 5

determine their boiling or melting points.