a) Why must you carry out the oxidation of Cu with HNO3 in a fume hood?
Concentrated nitric acid is a toxic oxidant. Avoiding skin contact or inhalation is highly important. The reaction between Cu and HNO3 produces NO2, a toxic brown gas; therefore working under the fume is necessary in order to prevent inhaling the toxic gas.
b) Why you should be particularly careful when you work with 3 M H2SO4 solution?
Sulfuric acid solution is a toxic oxidant. In under to prevent eye, skin, and clothing contact, it should be handled with care.
Briefly explain the meaning of each of the following terms as it relates to this experiment.
a) Decant: After reactions in parts III and V are complete, we isolate the metallic Cu and the CuO and we decant or pour off the supernatant liquid.
b) Filtrate: The liquid that passes through the filter in the step V will be the filtrate.
c) Supernatant liquid: The liquid above the settled precipitate of CuO in part III and Cu in part V. In these cases the liquid decanted.
3. Write the chemical equation(s) for each part of the following terms as it relates to this experiment.
(a) Part I
Cu(s) + 4H+ (aq) + 2NO3 – (aq) → Cu2+ (aq) + 2NO2(g) + 2H2O(l)
Cu(s, brown) + 4H3O+ (aq) + 2NO3 – (aq) → [Cu(H2O)6]2+ (aq, blue) + 2NO2 (g, gas)
(b) Part II
H3O+ (aq) + OH- (aq) → 2H2O(l)
[Cu(H2O)6]2+ (aq, blue) + 2 OH- (aq) → Cu(OH)2 (s, blue) + 6H2O (l)
(c) Part III
Cu(OH)2 (s, blue) CuO (s, black) + H2O (l)
(d) Part IV
CuO (s, black) + 2 H3O+ (aq) + 3 H2O (l) → [Cu(H2O)6]2+ (aq, blue)
(e) Part V
[Cu(H2O)6]2+ (aq, blue) + Zn(s, gray) → Cu(s, brown) + Zn2+ (aq, colorless) + 6H2O (l)
Zn(s, gray) + 2H3O+ (aq) → Zn2+ (aq, colorless) + H2(g) + 2H2O (l)
4 a. What test will you perform to determinate when you have added sufficient NaOH solution in Part II?
We will use red litmus paper, an acid base indicator that is red in acidic solution and