Research report: Sphalerite
By Jia Ni Zhou (Viola)

Section A a. The metals contained are Zinc, Iron, Palladium, Cadmium, lead. The main metal compounds found in it is ZnS. b. The extraction of Zinc from Sphalerite follows: (the flow diagram is on the next page.) Step 1: Sieving
The ore is firstly crushed and be able to be separated from the gangue.

Step 2: Froth Flotation
Since the concentration of zinc in natural ore is usually between 40%-50%. By using froth flotation, the percentage of ZnS rapidly increased.

Step 3: Roasting
High temperature is required to allow oxygen to react with Zinc sulphide. The following balanced equation shows the reaction, which is oxidation. The chemical balanced formula is stated below: 2ZnS (s) + 3O2 (g) → 2ZnO (l) + 2SO2 (g)

Step 4: Extraction by using chemical reactions
The use of carbon, mixed with ZnO under a hyperthermal environment produces the metal of Zinc with impurities. The chemical balanced formula is stated below: 2 ZnO (l) + C → 2 Zn (l) + CO2 (g)

Step 5: Evaporation
The ore changes its state as gas and leave the impurities behind. Step 6: Further purification Either fractional distillation or Electrolytic refining is applied to concentrate the impure zinc.

c. The whole procedure of two extractions are very similar. At the beginning of extraction, both ores are needed to be ground by crushing to get rid of gangue. In the following stage, they use the same separation technique, froth flotation, to concentrate the ore effectively. Since the main metal compound is CuFeS2, chalcopyrite needs one extra procedure here to remove Fe and produce CuS.
2CuFeS2 (s)+ 4O2 (g) = Cu2S (l) + 3SO2 (g) + 2FeO (s)
Next, the application of heating extracting the main metal compound out of the ore are identical.
2ZnS (s) + 3O2 (g) → 2ZnO (l) + 2SO2 (g)
2Cu2S (s) + 3O2 (g) → 2Cu2O (l) + 2SO2 (g)
Then the molten metal oxide in both extracting process is going to undergo the oxidation reaction.
2ZnO (l) + C → 2 Zn (l) + CO2 (g)
2Cu2S (l) + 3O2 → 2Cu2O (l) + 2 SO2 (g)
Ultimately, both have further process to concentrate the metal, such as electrolysis.

The flow diagram for extraction of Zinc (b.)
Section B a. | Zinc | Copper | Atomic structure | * 30 protons * 35 neutrons * 30 electrons arranged on four energy levels with the pattern 2,8,18,2. | * 29 protons * 35 neutrons * 29 electrons arranged on four energy levels with the pattern 2,8,18,1. | Reactivity | more reactive | less reactive | b. Although there is one more protons in atom of zinc providing a nuclear charge, the additional electron increases the shielding effect, which makes a greater atomic radius than that of atom of copper. The larger atomic size determines the property of high reactivity, therefore Zinc usually exists in compound in nature. In contrast, since the electron configuration of copper is similar to silver and gold, that there is not much shielding effect on the fourth energy level, so it is not a reactive metal for its stronger nuclear charge. What’s more, native copper can be found in nature but zinc doesn’t. Hence, the cost of production for copper is less than zinc because copper is unreactive. Besides, the commercial prices profoundly depends on the cost, it is apparent that copper is cheaper than zinc. c. ZnS
% (Zn) = 65.41/65.41+32.07 = 0.67100 = 67.10% d. Sphalerite ZnS: 1 kg 67.10% = 0.6710 kg
Chalcopyrite CuFeS2: % (Cu) = 63.55/ 63.55+55.85+232.07 = 34.62%
1 kg 34.62% = 0.3462 kg
∴ 0.6710 – 0.3462 = 0.3248 kg e. By using the formula % (A) = atomic mass of A / molecular mass of compound, we can accurately calculate the percentage of a specific element in gram. With this percentage, the mass of an element can be worked out in any quantity. This is because atomic weight is the mass of the atoms which made up of a matter, so it directly reflects the ratio of mass for the substance we can see in reality. Hence, the method I used in c. is valid.