H2O + Cl2 + KI = HCl + KIO3

H_2O water + Cl_2 chlorine + KI potassium iodide ⟶ HCl hydrogen chloride + KIO_3 potassium iodate

Balance the chemical equation algebraically: H_2O + Cl_2 + KI ⟶ HCl + KIO_3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O + c_2 Cl_2 + c_3 KI ⟶ c_4 HCl + c_5 KIO_3 Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, Cl, I and K: H: | 2 c_1 = c_4 O: | c_1 = 3 c_5 Cl: | 2 c_2 = c_4 I: | c_3 = c_5 K: | 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_3 = 1 and solve the system of equations for the remaining coefficients: c_1 = 3 c_2 = 3 c_3 = 1 c_4 = 6 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 H_2O + 3 Cl_2 + KI ⟶ 6 HCl + KIO_3

+ + ⟶ +

water + chlorine + potassium iodide ⟶ hydrogen chloride + potassium iodate

| water | chlorine | potassium iodide | hydrogen chloride | potassium iodate molecular enthalpy | -285.8 kJ/mol | 0 kJ/mol | -327.9 kJ/mol | -92.3 kJ/mol | -501.4 kJ/mol total enthalpy | -857.5 kJ/mol | 0 kJ/mol | -327.9 kJ/mol | -553.8 kJ/mol | -501.4 kJ/mol | H_initial = -1185 kJ/mol | | | H_final = -1055 kJ/mol | ΔH_rxn^0 | -1055 kJ/mol - -1185 kJ/mol = 130.2 kJ/mol (endothermic) | | | |

| water | chlorine | potassium iodide | hydrogen chloride | potassium iodate molecular free energy | -237.1 kJ/mol | 0 kJ/mol | -324.9 kJ/mol | -95.3 kJ/mol | -418.4 kJ/mol total free energy | -711.3 kJ/mol | 0 kJ/mol | -324.9 kJ/mol | -571.8 kJ/mol | -418.4 kJ/mol | G_initial = -1036 kJ/mol | | | G_final = -990.2 kJ/mol | ΔG_rxn^0 | -990.2 kJ/mol - -1036 kJ/mol = 46 kJ/mol (endergonic) | | | |

Construct the equilibrium constant, K, expression for: H_2O + Cl_2 + KI ⟶ HCl + KIO_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 + 3 Cl_2 + KI ⟶ 6 HCl + KIO_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 Cl_2 | 3 | -3 KI | 1 | -1 HCl | 6 | 6 KIO_3 | 1 | 1 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) Cl_2 | 3 | -3 | ([Cl2])^(-3) KI | 1 | -1 | ([KI])^(-1) HCl | 6 | 6 | ([HCl])^6 KIO_3 | 1 | 1 | [KIO3] 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) ([Cl2])^(-3) ([KI])^(-1) ([HCl])^6 [KIO3] = (([HCl])^6 [KIO3])/(([H2O])^3 ([Cl2])^3 [KI])

Construct the rate of reaction expression for: H_2O + Cl_2 + KI ⟶ HCl + KIO_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 + 3 Cl_2 + KI ⟶ 6 HCl + KIO_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 Cl_2 | 3 | -3 KI | 1 | -1 HCl | 6 | 6 KIO_3 | 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 H_2O | 3 | -3 | -1/3 (Δ[H2O])/(Δt) Cl_2 | 3 | -3 | -1/3 (Δ[Cl2])/(Δt) KI | 1 | -1 | -(Δ[KI])/(Δt) HCl | 6 | 6 | 1/6 (Δ[HCl])/(Δt) KIO_3 | 1 | 1 | (Δ[KIO3])/(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) = -1/3 (Δ[Cl2])/(Δt) = -(Δ[KI])/(Δt) = 1/6 (Δ[HCl])/(Δt) = (Δ[KIO3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| water | chlorine | potassium iodide | hydrogen chloride | potassium iodate formula | H_2O | Cl_2 | KI | HCl | KIO_3 Hill formula | H_2O | Cl_2 | IK | ClH | IKO_3 name | water | chlorine | potassium iodide | hydrogen chloride | potassium iodate IUPAC name | water | molecular chlorine | potassium iodide | hydrogen chloride | potassium iodate