FeCl3 = Cl2 + Fe

FeCl_3 iron(III) chloride ⟶ Cl_2 chlorine + Fe iron

Balance the chemical equation algebraically: FeCl_3 ⟶ Cl_2 + Fe Add stoichiometric coefficients, c_i, to the reactants and products: c_1 FeCl_3 ⟶ c_2 Cl_2 + c_3 Fe Set the number of atoms in the reactants equal to the number of atoms in the products for Cl and Fe: Cl: | 3 c_1 = 2 c_2 Fe: | c_1 = 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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 3/2 c_3 = 1 Multiply by the least common denominator, 2, to eliminate fractional coefficients: c_1 = 2 c_2 = 3 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 FeCl_3 ⟶ 3 Cl_2 + 2 Fe

⟶ +

iron(III) chloride ⟶ chlorine + iron

| iron(III) chloride | chlorine | iron molecular enthalpy | -399.5 kJ/mol | 0 kJ/mol | 0 kJ/mol total enthalpy | -799 kJ/mol | 0 kJ/mol | 0 kJ/mol | H_initial = -799 kJ/mol | H_final = 0 kJ/mol | ΔH_rxn^0 | 0 kJ/mol - -799 kJ/mol = 799 kJ/mol (endothermic) | |

Construct the equilibrium constant, K, expression for: FeCl_3 ⟶ Cl_2 + Fe 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: 2 FeCl_3 ⟶ 3 Cl_2 + 2 Fe 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 FeCl_3 | 2 | -2 Cl_2 | 3 | 3 Fe | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression FeCl_3 | 2 | -2 | ([FeCl3])^(-2) Cl_2 | 3 | 3 | ([Cl2])^3 Fe | 2 | 2 | ([Fe])^2 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 = ([FeCl3])^(-2) ([Cl2])^3 ([Fe])^2 = (([Cl2])^3 ([Fe])^2)/([FeCl3])^2

Construct the rate of reaction expression for: FeCl_3 ⟶ Cl_2 + Fe 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: 2 FeCl_3 ⟶ 3 Cl_2 + 2 Fe 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 FeCl_3 | 2 | -2 Cl_2 | 3 | 3 Fe | 2 | 2 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 FeCl_3 | 2 | -2 | -1/2 (Δ[FeCl3])/(Δt) Cl_2 | 3 | 3 | 1/3 (Δ[Cl2])/(Δt) Fe | 2 | 2 | 1/2 (Δ[Fe])/(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 = -1/2 (Δ[FeCl3])/(Δt) = 1/3 (Δ[Cl2])/(Δt) = 1/2 (Δ[Fe])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| iron(III) chloride | chlorine | iron formula | FeCl_3 | Cl_2 | Fe Hill formula | Cl_3Fe | Cl_2 | Fe name | iron(III) chloride | chlorine | iron IUPAC name | trichloroiron | molecular chlorine | iron

| iron(III) chloride | chlorine | iron molar mass | 162.2 g/mol | 70.9 g/mol | 55.845 g/mol phase | solid (at STP) | gas (at STP) | solid (at STP) melting point | 304 °C | -101 °C | 1535 °C boiling point | | -34 °C | 2750 °C density | | 0.003214 g/cm^3 (at 0 °C) | 7.874 g/cm^3 solubility in water | | | insoluble