This experiment served as a test of our individual laboratory skills in carrying out several chemical transformations involving copper. To recognize that change of state, change in color, formation of a precipitate, or the evolution of heat are associated with a chemical change; to study reactions of copper.
The experiment was successful in that the percent yield was reasonable, however we were not able to recover our copper sample with maximum efficiency ( we ended up with an excessive amount ).
The purpose of the experiment is to cycle solid copper through a series of five reactions. At different stages of the cycle, copper was present in different forms. First reaction involves reaction between the copper and nitric acid, and copper changed from elemental state to an aqueous. The second reaction converted the aqueous Cu into the solid copper hydroxide. In the third reaction Cu(OH)2 decomposed into copper 2 oxide and water when heated. When solid CuO reacted with sulfuric acid, the copper returned to solution as an ion (Cu2+). The cycle of reactions was completed with the reaction where elemental copper was regenerated by Zn and Cu exchanging states in acidic solution.
MATERIALS & METHODS
Apparatus. We utilized crucibles, crucible lids, clay triangle and the technique of bending down the edges of the triangle. This setup allowed us to expose Epsom salt to high heat in a vessel designed for high temperature exposure.
Reagents. We used a small carton of Epsom salt provided by the stockroom and a large blue bag of Epsom salt provided by the instructor.
Safety Considerations. Cold crucibles look the same as hot ones. We heated the hydrate gently at first because the water formed can sputter.
Procedures. At first we dried the crucible in the flame three times and let it come to a constant mass by measuring the weight each time. To determine percentage of water in Epsom salt, we measured about 2g of the salt into three different, dried...