Question

Compare the visual apperance of the original copper metal sample and the recovered sample. Based on their reaction with nitric acid, compare their chemical compositions.

Answer 1

1. copper is reddish brown in color when Copper react with Nitric acid then it formed copper nitrate.

Cu(s) + HNO₃ ===> Cu(NO₃)₂ + NO₂ + H₂O

2. Addition of Water produce [Cu(H₂O)₆]²⁺ which is of blue color.

  Cu(NO₃)₂ + 6H₂O ===> Cu(H₂O)₆²⁺  

3. Addition of NaOH produce Cu(OH)₂(s) which is light blue solid.

Cu(H₂O)₆²⁺ + 2OH^- ====> Cu(OH)₂ + 6H₂O

4. Heation of Cu(OH)₂produce CuO which is of black color.

Cu(OH)₂ + Heat =====> CuO + H₂O

5. Addition of CuO in H₂SO₄ , blue colored Cu(H₂O)₆²⁺ is formed .

CuO + H₃O⁺ ====> Cu(H₂O)₆²⁺

6. Adiition of Mg in Cu(H₂O)₆²⁺ produce solid copper.

Cu(H₂O)₆²⁺ + Mg ====> Cu(s) + Mg²⁺ + 6H₂O

In the following above sequences we got copper recovered as it was present intially . Atfer all these sequence we got pure copper of browm reddish color. So by using these sequence of reaction we can extract the pure copper from any compoind.