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How can I make the copper get white by any salt or acit?I have some test on the copper

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sadsen | Student, College Freshman | eNotes Newbie

Posted May 11, 2011 at 8:50 PM via web

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

I have some test on the copper

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giorgiana1976 | College Teacher | Valedictorian

Posted May 12, 2011 at 12:05 AM (Answer #1)

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The copper sulfate compound (CuSO4) is a salt and it is used to illustrate the inorganic chemical reaction called mineral hydration.

The pentahydrate copper sulfate usually has a blue color.

When pentahydrate copper sulfate is heated, to prove the exothermic reaction, the water inside evaporates, leaving behind a new anhydrous form whose color is white.

If water is added to the new anhydrous form, it will become the original blue pentahydrate copper sulfate.

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govindan | College Teacher | eNoter

Posted May 28, 2011 at 3:28 PM (Answer #2)

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Do you mean it as Copper metal metal? If yes, 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 (NH4CNS) salt solution to give the white (colourless) precipitate of copper thiocyanate Cu(CNS)2.

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malika786 | Student, Grade 11 | Honors

Posted May 11, 2011 at 11:53 PM (Answer #3)

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hydrogen sulphide because its not stable and gets oxidized in air........!

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