ZnCl2 + FeS = FeCl2 + ZnS

ZnCl_2 zinc chloride + FeS ferrous sulfide ⟶ FeCl_2 iron(II) chloride + ZnS zinc sulfide

Balance the chemical equation algebraically: ZnCl_2 + FeS ⟶ FeCl_2 + ZnS Add stoichiometric coefficients, c_i, to the reactants and products: c_1 ZnCl_2 + c_2 FeS ⟶ c_3 FeCl_2 + c_4 ZnS Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, Zn, Fe and S: Cl: | 2 c_1 = 2 c_3 Zn: | c_1 = c_4 Fe: | c_2 = c_3 S: | c_2 = c_4 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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 1 c_3 = 1 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | ZnCl_2 + FeS ⟶ FeCl_2 + ZnS

+ ⟶ +

zinc chloride + ferrous sulfide ⟶ iron(II) chloride + zinc sulfide

| zinc chloride | ferrous sulfide | iron(II) chloride | zinc sulfide molecular enthalpy | -415.1 kJ/mol | -100 kJ/mol | -341.8 kJ/mol | -206 kJ/mol total enthalpy | -415.1 kJ/mol | -100 kJ/mol | -341.8 kJ/mol | -206 kJ/mol | H_initial = -515.1 kJ/mol | | H_final = -547.8 kJ/mol | ΔH_rxn^0 | -547.8 kJ/mol - -515.1 kJ/mol = -32.7 kJ/mol (exothermic) | | |

| zinc chloride | ferrous sulfide | iron(II) chloride | zinc sulfide molecular free energy | -369.4 kJ/mol | -100.4 kJ/mol | -302.3 kJ/mol | -201 kJ/mol total free energy | -369.4 kJ/mol | -100.4 kJ/mol | -302.3 kJ/mol | -201 kJ/mol | G_initial = -469.8 kJ/mol | | G_final = -503.3 kJ/mol | ΔG_rxn^0 | -503.3 kJ/mol - -469.8 kJ/mol = -33.5 kJ/mol (exergonic) | | |

Construct the equilibrium constant, K, expression for: ZnCl_2 + FeS ⟶ FeCl_2 + ZnS 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: ZnCl_2 + FeS ⟶ FeCl_2 + ZnS 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 ZnCl_2 | 1 | -1 FeS | 1 | -1 FeCl_2 | 1 | 1 ZnS | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression ZnCl_2 | 1 | -1 | ([ZnCl2])^(-1) FeS | 1 | -1 | ([FeS])^(-1) FeCl_2 | 1 | 1 | [FeCl2] ZnS | 1 | 1 | [ZnS] 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 = ([ZnCl2])^(-1) ([FeS])^(-1) [FeCl2] [ZnS] = ([FeCl2] [ZnS])/([ZnCl2] [FeS])

Construct the rate of reaction expression for: ZnCl_2 + FeS ⟶ FeCl_2 + ZnS 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: ZnCl_2 + FeS ⟶ FeCl_2 + ZnS 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 ZnCl_2 | 1 | -1 FeS | 1 | -1 FeCl_2 | 1 | 1 ZnS | 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 ZnCl_2 | 1 | -1 | -(Δ[ZnCl2])/(Δt) FeS | 1 | -1 | -(Δ[FeS])/(Δt) FeCl_2 | 1 | 1 | (Δ[FeCl2])/(Δt) ZnS | 1 | 1 | (Δ[ZnS])/(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 = -(Δ[ZnCl2])/(Δt) = -(Δ[FeS])/(Δt) = (Δ[FeCl2])/(Δt) = (Δ[ZnS])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| zinc chloride | ferrous sulfide | iron(II) chloride | zinc sulfide formula | ZnCl_2 | FeS | FeCl_2 | ZnS Hill formula | Cl_2Zn | FeS | Cl_2Fe | SZn name | zinc chloride | ferrous sulfide | iron(II) chloride | zinc sulfide IUPAC name | zinc dichloride | | dichloroiron | thioxozinc

| zinc chloride | ferrous sulfide | iron(II) chloride | zinc sulfide molar mass | 136.3 g/mol | 87.9 g/mol | 126.7 g/mol | 97.44 g/mol phase | solid (at STP) | solid (at STP) | solid (at STP) | solid (at STP) melting point | 293 °C | 1195 °C | 677 °C | 1064 °C density | | 4.84 g/cm^3 | 3.16 g/cm^3 | 4.1 g/cm^3 solubility in water | soluble | insoluble | | dynamic viscosity | | 0.00343 Pa s (at 1250 °C) | | odor | odorless | | |