H2O + FeCl3 + Na2CO3 = CO2 + NaCl + Fe(OH)3

H_2O water + FeCl_3 iron(III) chloride + Na_2CO_3 soda ash ⟶ CO_2 carbon dioxide + NaCl sodium chloride + Fe(OH)_3 iron(III) hydroxide

Balance the chemical equation algebraically: H_2O + FeCl_3 + Na_2CO_3 ⟶ CO_2 + NaCl + Fe(OH)_3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O + c_2 FeCl_3 + c_3 Na_2CO_3 ⟶ c_4 CO_2 + c_5 NaCl + c_6 Fe(OH)_3 Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, Cl, Fe, C and Na: H: | 2 c_1 = 3 c_6 O: | c_1 + 3 c_3 = 2 c_4 + 3 c_6 Cl: | 3 c_2 = c_5 Fe: | c_2 = c_6 C: | c_3 = c_4 Na: | 2 c_3 = c_5 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 = 3/2 c_2 = 1 c_3 = 3/2 c_4 = 3/2 c_5 = 3 c_6 = 1 Multiply by the least common denominator, 2, to eliminate fractional coefficients: c_1 = 3 c_2 = 2 c_3 = 3 c_4 = 3 c_5 = 6 c_6 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 H_2O + 2 FeCl_3 + 3 Na_2CO_3 ⟶ 3 CO_2 + 6 NaCl + 2 Fe(OH)_3

+ + ⟶ + +

water + iron(III) chloride + soda ash ⟶ carbon dioxide + sodium chloride + iron(III) hydroxide

Construct the equilibrium constant, K, expression for: H_2O + FeCl_3 + Na_2CO_3 ⟶ CO_2 + NaCl + Fe(OH)_3 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 H_2O + 2 FeCl_3 + 3 Na_2CO_3 ⟶ 3 CO_2 + 6 NaCl + 2 Fe(OH)_3 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 H_2O | 3 | -3 FeCl_3 | 2 | -2 Na_2CO_3 | 3 | -3 CO_2 | 3 | 3 NaCl | 6 | 6 Fe(OH)_3 | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2O | 3 | -3 | ([H2O])^(-3) FeCl_3 | 2 | -2 | ([FeCl3])^(-2) Na_2CO_3 | 3 | -3 | ([Na2CO3])^(-3) CO_2 | 3 | 3 | ([CO2])^3 NaCl | 6 | 6 | ([NaCl])^6 Fe(OH)_3 | 2 | 2 | ([Fe(OH)3])^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 = ([H2O])^(-3) ([FeCl3])^(-2) ([Na2CO3])^(-3) ([CO2])^3 ([NaCl])^6 ([Fe(OH)3])^2 = (([CO2])^3 ([NaCl])^6 ([Fe(OH)3])^2)/(([H2O])^3 ([FeCl3])^2 ([Na2CO3])^3)

Construct the rate of reaction expression for: H_2O + FeCl_3 + Na_2CO_3 ⟶ CO_2 + NaCl + Fe(OH)_3 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 H_2O + 2 FeCl_3 + 3 Na_2CO_3 ⟶ 3 CO_2 + 6 NaCl + 2 Fe(OH)_3 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 H_2O | 3 | -3 FeCl_3 | 2 | -2 Na_2CO_3 | 3 | -3 CO_2 | 3 | 3 NaCl | 6 | 6 Fe(OH)_3 | 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 H_2O | 3 | -3 | -1/3 (Δ[H2O])/(Δt) FeCl_3 | 2 | -2 | -1/2 (Δ[FeCl3])/(Δt) Na_2CO_3 | 3 | -3 | -1/3 (Δ[Na2CO3])/(Δt) CO_2 | 3 | 3 | 1/3 (Δ[CO2])/(Δt) NaCl | 6 | 6 | 1/6 (Δ[NaCl])/(Δt) Fe(OH)_3 | 2 | 2 | 1/2 (Δ[Fe(OH)3])/(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[H2O])/(Δt) = -1/2 (Δ[FeCl3])/(Δt) = -1/3 (Δ[Na2CO3])/(Δt) = 1/3 (Δ[CO2])/(Δt) = 1/6 (Δ[NaCl])/(Δt) = 1/2 (Δ[Fe(OH)3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| water | iron(III) chloride | soda ash | carbon dioxide | sodium chloride | iron(III) hydroxide formula | H_2O | FeCl_3 | Na_2CO_3 | CO_2 | NaCl | Fe(OH)_3 Hill formula | H_2O | Cl_3Fe | CNa_2O_3 | CO_2 | ClNa | FeH_3O_3 name | water | iron(III) chloride | soda ash | carbon dioxide | sodium chloride | iron(III) hydroxide IUPAC name | water | trichloroiron | disodium carbonate | carbon dioxide | sodium chloride | ferric trihydroxide