O2 + CuFeS2 = SO2 + CuO + FeO

O_2 oxygen + CuFeS_2 copper(II) ferrous sulfide ⟶ SO_2 sulfur dioxide + CuO cupric oxide + FeO iron(II) oxide

Balance the chemical equation algebraically: O_2 + CuFeS_2 ⟶ SO_2 + CuO + FeO Add stoichiometric coefficients, c_i, to the reactants and products: c_1 O_2 + c_2 CuFeS_2 ⟶ c_3 SO_2 + c_4 CuO + c_5 FeO Set the number of atoms in the reactants equal to the number of atoms in the products for O, Cu, Fe and S: O: | 2 c_1 = 2 c_3 + c_4 + c_5 Cu: | c_2 = c_4 Fe: | c_2 = c_5 S: | 2 c_2 = c_3 Since the coefficients are relative quantities and underdetermined, choose a coefficient to set arbitrarily. To keep the coefficients small, the arbitrary value is ordinarily one. For instance, set c_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 3 c_2 = 1 c_3 = 2 c_4 = 1 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 O_2 + CuFeS_2 ⟶ 2 SO_2 + CuO + FeO

+ CuFeS_2 ⟶ + +

oxygen + copper(II) ferrous sulfide ⟶ sulfur dioxide + cupric oxide + iron(II) oxide

Construct the equilibrium constant, K, expression for: O_2 + CuFeS_2 ⟶ SO_2 + CuO + FeO Plan: • Balance the chemical equation. • Determine the stoichiometric numbers. • Assemble the activity expression for each chemical species. • Use the activity expressions to build the equilibrium constant expression. Write the balanced chemical equation: 3 O_2 + CuFeS_2 ⟶ 2 SO_2 + CuO + FeO Assign stoichiometric numbers, ν_i, using the stoichiometric coefficients, c_i, from the balanced chemical equation in the following manner: ν_i = -c_i for reactants and ν_i = c_i for products: chemical species | c_i | ν_i O_2 | 3 | -3 CuFeS_2 | 1 | -1 SO_2 | 2 | 2 CuO | 1 | 1 FeO | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression O_2 | 3 | -3 | ([O2])^(-3) CuFeS_2 | 1 | -1 | ([CuFeS2])^(-1) SO_2 | 2 | 2 | ([SO2])^2 CuO | 1 | 1 | [CuO] FeO | 1 | 1 | [FeO] The equilibrium constant symbol in the concentration basis is: K_c Mulitply the activity expressions to arrive at the K_c expression: Answer: | | K_c = ([O2])^(-3) ([CuFeS2])^(-1) ([SO2])^2 [CuO] [FeO] = (([SO2])^2 [CuO] [FeO])/(([O2])^3 [CuFeS2])

Construct the rate of reaction expression for: O_2 + CuFeS_2 ⟶ SO_2 + CuO + FeO Plan: • Balance the chemical equation. • Determine the stoichiometric numbers. • Assemble the rate term for each chemical species. • Write the rate of reaction expression. Write the balanced chemical equation: 3 O_2 + CuFeS_2 ⟶ 2 SO_2 + CuO + FeO Assign stoichiometric numbers, ν_i, using the stoichiometric coefficients, c_i, from the balanced chemical equation in the following manner: ν_i = -c_i for reactants and ν_i = c_i for products: chemical species | c_i | ν_i O_2 | 3 | -3 CuFeS_2 | 1 | -1 SO_2 | 2 | 2 CuO | 1 | 1 FeO | 1 | 1 The rate term for each chemical species, B_i, is 1/ν_i(Δ[B_i])/(Δt) where [B_i] is the amount concentration and t is time: chemical species | c_i | ν_i | rate term O_2 | 3 | -3 | -1/3 (Δ[O2])/(Δt) CuFeS_2 | 1 | -1 | -(Δ[CuFeS2])/(Δt) SO_2 | 2 | 2 | 1/2 (Δ[SO2])/(Δt) CuO | 1 | 1 | (Δ[CuO])/(Δt) FeO | 1 | 1 | (Δ[FeO])/(Δt) (for infinitesimal rate of change, replace Δ with d) Set the rate terms equal to each other to arrive at the rate expression: Answer: | | rate = -1/3 (Δ[O2])/(Δt) = -(Δ[CuFeS2])/(Δt) = 1/2 (Δ[SO2])/(Δt) = (Δ[CuO])/(Δt) = (Δ[FeO])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| oxygen | copper(II) ferrous sulfide | sulfur dioxide | cupric oxide | iron(II) oxide formula | O_2 | CuFeS_2 | SO_2 | CuO | FeO Hill formula | O_2 | CuFeS_2 | O_2S | CuO | FeO name | oxygen | copper(II) ferrous sulfide | sulfur dioxide | cupric oxide | iron(II) oxide IUPAC name | molecular oxygen | | sulfur dioxide | | oxoiron