Copper exists in the form of \(\mathrm{CuFeS}_{2}\) in copper ore. Copper is isolated in a two-step process. First, CuFeS \(_{2}\) is heated with \(\mathrm{SiO}_{2}\) in the presence of oxygen to form copper(I) sulfide, $\mathrm{CuS:} 2 \mathrm{CuFeS}_{2}+2 \mathrm{SiO}_{2}(s)+4 \mathrm{O}_{2}(g) \longrightarrow \mathrm{Cu}_{2} \mathrm{~S}(s)+$ \(2 \mathrm{FeSiO}_{3}(s)+3 \mathrm{SO}_{2}(g) . \mathrm{Cu}_{2} \mathrm{~S}\) is then heated with oxygen to form copper and \(\mathrm{SO}_{2}(g)\). (a) Write the balanced chemical equation for the second reaction. (b) Which atoms from which compounds are being oxidized, and which atoms from which compounds are being reduced? (c) How many grams of copper would be isolated from \(85.36 \mathrm{~g}\) of \(\mathrm{CuFeS}_{2}\) in copper ore?

We are given that Cu₂S is heated with oxygen to form copper and SO₂. To write the balanced chemical equation, we need to balance all atoms on both sides of the equation. Since there are 2 copper atoms and 1 sulfur atom on the left-hand side, we require 2 copper atoms and 1 sulfur atom on the right-hand side as well: 2 Cu₂S(s) + 3 O₂(g) → 4 Cu(s) + 2 SO₂(g)

In the first reaction, CuFeS₂ is heated with SiO₂ in the presence of oxygen to form Cu₂S, FeSiO₃, and SO₂. The species being oxidized and reduced can be identified by analyzing the change in their oxidation states: - Cu: goes from +1 in CuFeS₂ to 0 in Cu (reduced) - Fe: goes from +2 in CuFeS₂ to +3 in FeSiO₃ (oxidized) - S: goes from -2 in CuFeS₂ to +4 in SO₂ (oxidized) Thus, Cu is being reduced, while Fe and S are being oxidized.

We are given that 85.36 g of CuFeS₂ is used in copper ore. To determine the amount of copper isolated, we need to convert the mass of CuFeS₂ to mole and then use stoichiometry to convert moles of CuFeS₂ to moles of copper. Finally, we will convert moles of copper back to mass (grams). 1. Calculate the molar mass of CuFeS₂: M(CuFeS₂) = Atomic Mass of Cu + Atomic Mass of Fe + 2 * Atomic Mass of S M(CuFeS₂) = 63.55 g/mol + 55.85 g/mol + 2 * 32.07 g/mol = 183.54 g/mol 2. Convert mass of CuFeS₂ to moles: moles of CuFeS₂ = (mass of CuFeS₂) / (molar mass of CuFeS₂) moles of CuFeS₂ = 85.36 g / 183.54 g/mol = 0.4649 mol 3. Convert moles of CuFeS₂ to moles of Cu using stoichiometry (from the balanced chemical equation in Step 1): moles of Cu = 2 * moles of CuFeS₂ (since coefficent of Cu₂S is 2 and coefficent of Cu is 4 in the balanced chemical equation) moles of Cu = 2 * 0.4649 mol = 0.9298 mol 4. Convert moles of Cu back to mass in grams: mass of Cu = moles of Cu * Atomic Mass of Cu mass of Cu = 0.9298 mol * 63.55 g/mol = 59.13 g Hence, 59.13 g of copper would be isolated from 85.36 g of CuFeS₂ in copper ore.