Copper Cycle Post Lab Questions

CHEM 53 Experiment 1: Series of Copper Reactions

Discussion Questions

Discussion Questions:

1. For reaction # 5, how does your data support the reaction that you claim occurred. Cite specific observations that suggest your reaction is correct.

The data supports the reaction occurred due to the presence of a bright blue translucent liquid at the conclusion of the reaction. This represents the CuSO4 (aq) that was produced as a result of the reaction. Also the lack of any precipitate clearly indicates CuO (s) dissolved.

2. Similar to question one, discuss how your data supports your claim for the two parts of reaction 6.

The data supports the reaction occurred due to the formation of a dark precipitate and a solution clear in color. The dark precipitate represents the Cu (s) and the clear solution represents the ZnSO4 (aq). The evidence of a gas bubbling out of the solution supports the second part of the reaction. The gas represents the H2 (g) and the support for the product Zn^2+ (aq) is given as it had to serve as the cation for ZnSO4.

3. In this experiment, reactions in the first step and the last step are redox reactions. For the reaction in Step 1, identify the reactants according to their behavior (hint: classify the reactants as one of the two types of "agents" associated with redox)

Cu (s) is the reducing agent. Initially Cu (s) has an oxidation number of 0. After the reaction occurs Cu (s) has an oxidation number of 2. Nitric acid, the other reactant, is the oxidizing agent in this reaction.

4. The copper recovered at the end of the experiment may not appear to be shiny and may, in fact, appear as a dark precipitate. Why?

The explanation for the appearance of a dark precipitate is that there may be traces of CuO on the copper. Due to these reactions being conducted in environments rich in oxygen it would be difficult to completely rid the experiment of CuO at the conclusion of the reactions....