Sulfur
(Sulfides)
S
atomic number
16
melting point
115.21°C

1. Place a small amount of finely powdered mineral in an open tube, then apply a hot flame to the bottom of the tube; pungent fumes of SO2 gas will emanate from the tube; (the presence of SO2 is confirmed if a piece of moistened litmus paper turns red when exposed to the fumes); this reaction occurs for most sulfides; the iron and copper sulfides produce a similar reaction when heated in an open tube; in this case, small droplets of sulfuric acid will begin to condense on the sides of the test tube as dense white fumes of SO3 gas are emitted.

2. Pour a small quantity of powdered mineral into a large test tube containing concentrated nitric acid; small droplets of sulfuric acid will begin to condense on the sides of the test tube as copious red fumes of NO2 gas are emitted; (a residue of elemental sulfur is sometimes left floating on the surface of the solution).

3. Pour a small quantity of powdered mineral into a large test tube containing concentrated HCl; some sulfides produce unpleasant fumes of H2S gas when treated in this fashion.