Copper

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Marie Remy
Lab 02/19/13
Purpose
     To explore the cycle of copper through many chemical reactions. What we are going to do is take a piece of copper metal put it through a series of reactions that change it¡¦s state of matter and chemical formula, but in the end, we will return it to it¡¦s normal solid state. Determine the percentage yield (quantitative). Define what happen at level of electron for oxidation/reduction, double replacement, neutralization and decomposition. There are five reactions that the copper will go through. 1.     Cu(s) + 4HNO3(aq) --- Cu(NO3)2(aq) + 2H2O(aq) + NO2(aq) 2.     HNO3(aq) + NaOH(aq)--NaNO3(aq) + H20(l)

3.     Cu(OH)2(s)--CuO(s) + H2O(l)
4.     CuO(s) + H2SO4(aq)-- CuSO4(aq) +H2O(l)
5.     CuSO4(aq) + Zn(s)-- ZnSO4(aq) + Cu(s)

At the end of reaction number five we should have close to 100% of the copper we started out with.

Result
Original Mass of Cu=.452g
Mass of Cycled Cu=2.483g

1.     In the first reaction oxidation-reduction occurs there were a brown smoke has the Cu dissolves, after adding 100ml of H2O, 2.     In the second reaction the solution turned into a clear blue liquid, neutralization reaction occurs. 3.     In the third decomposition reaction when the solution was heated a blue jelly formed and then a black precipitate formed at the bottom of the beaker. 4.     In the fourth reaction the black precipitate turned into a light blue liquid once again, which is called double replacement reaction. 5.     In the final reaction the clear blue liquid turned into a copper colored metal, known as copper. Oxidation-reduction reaction

Calculation
Percent yield =
Mass of recovered copper ÷ initial mass of copper × 100 = 54.9%=2.483g/.452g * 100

Conclusion
We recovered 54.9%. We did not recover as much copper, one of the problems may have been made when drying the copper, and not letting enough of the water evaporate, and this could lead to a falsely low percent recovery. But...
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