KOH + FeCl2 = KCl + Fe(OH)2

KOH potassium hydroxide + FeCl_2 iron(II) chloride ⟶ KCl potassium chloride + Fe(OH)_2 iron(II) hydroxide

Balance the chemical equation algebraically: KOH + FeCl_2 ⟶ KCl + Fe(OH)_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 KOH + c_2 FeCl_2 ⟶ c_3 KCl + c_4 Fe(OH)_2 Set the number of atoms in the reactants equal to the number of atoms in the products for H, K, O, Cl and Fe: H: | c_1 = 2 c_4 K: | c_1 = c_3 O: | c_1 = 2 c_4 Cl: | 2 c_2 = c_3 Fe: | 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 1 c_3 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 KOH + FeCl_2 ⟶ 2 KCl + Fe(OH)_2

+ ⟶ +

potassium hydroxide + iron(II) chloride ⟶ potassium chloride + iron(II) hydroxide

Construct the equilibrium constant, K, expression for: KOH + FeCl_2 ⟶ KCl + Fe(OH)_2 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 KOH + FeCl_2 ⟶ 2 KCl + Fe(OH)_2 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 KOH | 2 | -2 FeCl_2 | 1 | -1 KCl | 2 | 2 Fe(OH)_2 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression KOH | 2 | -2 | ([KOH])^(-2) FeCl_2 | 1 | -1 | ([FeCl2])^(-1) KCl | 2 | 2 | ([KCl])^2 Fe(OH)_2 | 1 | 1 | [Fe(OH)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 = ([KOH])^(-2) ([FeCl2])^(-1) ([KCl])^2 [Fe(OH)2] = (([KCl])^2 [Fe(OH)2])/(([KOH])^2 [FeCl2])

Construct the rate of reaction expression for: KOH + FeCl_2 ⟶ KCl + Fe(OH)_2 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 KOH + FeCl_2 ⟶ 2 KCl + Fe(OH)_2 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 KOH | 2 | -2 FeCl_2 | 1 | -1 KCl | 2 | 2 Fe(OH)_2 | 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 KOH | 2 | -2 | -1/2 (Δ[KOH])/(Δt) FeCl_2 | 1 | -1 | -(Δ[FeCl2])/(Δt) KCl | 2 | 2 | 1/2 (Δ[KCl])/(Δt) Fe(OH)_2 | 1 | 1 | (Δ[Fe(OH)2])/(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[KOH])/(Δt) = -(Δ[FeCl2])/(Δt) = 1/2 (Δ[KCl])/(Δt) = (Δ[Fe(OH)2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| potassium hydroxide | iron(II) chloride | potassium chloride | iron(II) hydroxide formula | KOH | FeCl_2 | KCl | Fe(OH)_2 Hill formula | HKO | Cl_2Fe | ClK | FeH_2O_2 name | potassium hydroxide | iron(II) chloride | potassium chloride | iron(II) hydroxide IUPAC name | potassium hydroxide | dichloroiron | potassium chloride | ferrous dihydroxide