Answer to Question #2799 in Inorganic Chemistry for sadsen

Question

How can I make the copper get white by salt or acit?

Answer 1

the metal copper is first converted to blue coloured copper sulphate by the
reaction with concentrated sulphuric acid.
Cu + H₂SO₄ --> CuSO₄ (aq) (Blue)

the solution on evapourasion gives the Blue crystals of CuSO₄*5H₂O which on
further heating gives anhydrous CuSO4 which is colourless.
CuSO₄*5H₂O Blue --Heating --> CuSO₄ white + 5H₂O

Other method is the blue coppersulphate solution will react with ammonium
thiocyanate (NH₄NCS) salt solution to give the white (colourless)
precipitate of copper thiocyanate Cu(NCS)₂.