[apricot]

Guys I need just a clue. To make sulphur dioxide gas one needs to drop conc. H2SO4 on copper turnings, right? then the gases produced are bubbled through conc. H2SO4, but for what reason? SO2 can then be collected.
Also, apart from this is there any other way in which SO2 can be prepared in the small scale in the lab, without using electrolysis?

Thanks

[Arkcon]

I'm not 100% sure that H₂SO₄ evolves SO₂ when mixed with copper, it may, I've just never heard of that particular recipie for SO₂.  The conc. H₂SO₄ is a classical way to dry moist vapor, which you get whenever you try to generate a gas by fizzing it out from an aqueous solution.  Another way to generate SO₂ is to simply burn sulfur, in air.  There's no competing reactions, and the SO₂ you get is moisture free.  I hope your ready and equipped to handle this noxious gas.

[Borek]

Drying and perhaps removing SO₃ traces (well soluble in concentrated sulfuric acid).

[srb]

Sulphur Dioxide can be prepared in the laboratory with copper turnings. The reaction is Cu + 2H2SO4 -> CuSO4 + SO2 (gas) + 2H2O. Then SO2 is dried using Sulphuric Acid. After this Sulphur Dioxide gas can be collected by the upward displacement of air. On a small scale, when Sulphur is burnt in Oxygen, SO2 gas is formed. Or else Galena, Iron or Copper pyrites or Zinc Blende can be burnt in Oxygen to yield Sulphur Dioxide.