1- A variety of procedural errors can impact the effectiveness of the copper reaction cycle. Comment on the following documented errors: a. When NaOH (aq) is added to the Cu(NO3)2 solution in Reaction B, the Cu(OH)2 (s) occasionally does not precipitate immediately, and excess NaOH must be added. What other substance present in the reaction mixture might preferentially react with the NaOH and prevent precipitation of the Cu(OH)2? Explain.
b. Students sometimes use HNO3 (aq) instead of H2SO4 (aq) in Reaction E, Step 4, assuming that both strong acids will accomplish the same purpose. Briefly describe the consequences of this error.
2. Students occasionally observe the formation of a solid white side product, sometimes appearing as a white residue on the walls of the test tube, in the recovery and isolation of the copper metal in Reaction E. Speculate on the identity of this white solid. (Use of online resources may be helpful.)
3. Errors in experimental technique can result in the percent recovery of copper being too low or too high. Give at least one specific example of each type of error in technique, and explain what could be done to ensure that those errors do not occur in the recovery.
4. Comment on the percent recovery of copper achieved by your group. Indicate whether it was less than 100% or greater than 100%. Do any of the explanations provided in Question 3 apply to the results you obtained?