In this experiment, copper will undergo a series of chemical transformations. A summary of chemical reactions is written below: Cu (s) [Cu(H 2 O) 6 ] 2+ (aq) Cu(OH) 2 (s) CuO (s) [Cu(H 2 O) 6 ] 2+ (aq) Cu (s)
The chemical reactions will transform copper into various physical forms, but since the transformation is done in sequence, copper will be recovered at the end.
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Oxidizing Copper with concentrated nitric acid (HNO 3 ) solution.
0.716 grams of copper wire is reacted with 2.5-3.0ml of concentrated nitric acid (HNO 3 ) solution. Cu (s) + 4 H30 + (aq) + 2 NO 3 - [Cu(H 2 O) 6 ] 2+ (aq) + 2 NO 2 (g)
Observations:
Copper wire disappears.
A blue solution is formed ([Cu(H 2 O) 6 ] 2+ ).
A brown gas is produced (NO 2 ).
Precipitating [Cu(H 2 O) 6 ] 2+ (aq) with sodium hydroxide (NaOH)
6M of sodium hydroxide solution (NaOH) is added to an aqueous blue solution containing copper (II) ions to form the insoluble copper (II) hydroxide (Cu(OH) 2 ). [Cu(H 2 O) 6 ] 2 (aq) + 2 OH - Cu(OH) 2 (s) + 6 H 2 O (l)
Observations:
A light blue precipitate; Cu(OH) 2 (s).
A clear solution; 6 H 2 O (l).
Preparation of copper (II) oxide (CuO).
Heat decomposes Copper hydroxide (Cu(OH) 2 ) to copper (II) oxide (CuO) and water (H 2 O). Cu(OH) 2 (s) + heat CuO (s) + H 2 O (l)
Observations:
The light blue precipitate (Cu(OH) 2 ) changes to a black solid (CuO).
A clear solution is formed (H 2 O).
Synthesis reaction.
Copper oxide (CuO) is dissolved in 3M sulfuric acid solution (H 2 SO 4 ) to obtain copper (II) ion ([Cu(H 2 O) 6 ] 2+ ). CuO (s) +2 H 3 O + (aq) + 3 H 2 O (l) [Cu(H 2 O) 6 ] 2+ (aq)
Observations:
The black CuO will disappear and a blue solution ([Cu(H 2 O) 6 ] 2+ ) is formed once again.
Reducing copper (II) ion ([Cu(H 2 O) 6 ] 2+ ) to copper wire with magnesium granules.
Magnesium granules reduce the hydrated copper (II) ions to 0.65g copper wire. The magnesium granules are oxidized to magnesium (II) ions (Mg 2+ ) while the copper (II) ions are reduced to copper. [Cu(H 2 O) 6 ] 2+ (aq) + Mg (s) Cu (s) + Mg 2+ (aq) + 6 H 2 O (aq)
Observations:
The blue color disappears completely at the end of the reaction and a clear solution is formed (H 2 O).
Copper wire can be seen in the clear solution (Cu).
Finally, the mass percent of the recovered copper is calculated to evaluate the efficiency of the transformation sequence. At the end of this experiment, 90.8% of copper was recovered. The data did conform to what was expected as 100% of copper was not recovered. This is mainly because of experimental error.
Conclusion.
The five sequence of chemical reactions involving copper was efficient.
References
Beatty, R. (2001). Copper. New York: Benchmark Books.
Johansson, A. J., & Brinck, T. (2012). Mechanisms and energetics of surface reactions at the copper-water interface. TR-12-07, Swedish Nuclear Fuel Management Co., Stockholm, Sweden.
Pilgaard, M. (January, 2016). Cooper chemical reactions. Retrieved from https://pilgaardelements.com/Copper/Reactions.htm .
Richards, J. (2008). Chemicals & reactions. New York: PowerKids Press.
Schlesinger, M. E., King, M. J., Sole, K. C., & Davenport, W. G. (2011). Extractive metallurgy of copper. Amsterdam: Elsevier.
Williams, R. (September, 2015). Transformation of Copper: A Sequence of Chemical Reactions. Retrieved from https://web.lemoyne.edu/giunta/chm151L/copper.html .
