HCl + KClO3 = H2O + Cl2 + KCl

HCl (hydrogen chloride) + KClO_3 (potassium chlorate) ⟶ H_2O (water) + Cl_2 (chlorine) + KCl (potassium chloride)

Balance the chemical equation algebraically: HCl + KClO_3 ⟶ H_2O + Cl_2 + KCl Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HCl + c_2 KClO_3 ⟶ c_3 H_2O + c_4 Cl_2 + c_5 KCl Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, H, K and O: Cl: | c_1 + c_2 = 2 c_4 + c_5 H: | c_1 = 2 c_3 K: | c_2 = c_5 O: | 3 c_2 = 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 6 c_2 = 1 c_3 = 3 c_4 = 3 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 6 HCl + KClO_3 ⟶ 3 H_2O + 3 Cl_2 + KCl

+ ⟶ + +

hydrogen chloride + potassium chlorate ⟶ water + chlorine + potassium chloride

| hydrogen chloride | potassium chlorate | water | chlorine | potassium chloride molecular enthalpy | -92.3 kJ/mol | -397.7 kJ/mol | -285.8 kJ/mol | 0 kJ/mol | -436.5 kJ/mol total enthalpy | -553.8 kJ/mol | -397.7 kJ/mol | -857.5 kJ/mol | 0 kJ/mol | -436.5 kJ/mol | H_initial = -951.5 kJ/mol | | H_final = -1294 kJ/mol | | ΔH_rxn^0 | -1294 kJ/mol - -951.5 kJ/mol = -342.5 kJ/mol (exothermic) | | | |

| hydrogen chloride | potassium chlorate | water | chlorine | potassium chloride molecular free energy | -95.3 kJ/mol | -296.3 kJ/mol | -237.1 kJ/mol | 0 kJ/mol | -408.5 kJ/mol total free energy | -571.8 kJ/mol | -296.3 kJ/mol | -711.3 kJ/mol | 0 kJ/mol | -408.5 kJ/mol | G_initial = -868.1 kJ/mol | | G_final = -1120 kJ/mol | | ΔG_rxn^0 | -1120 kJ/mol - -868.1 kJ/mol = -251.7 kJ/mol (exergonic) | | | |

| hydrogen chloride | potassium chlorate | water | chlorine | potassium chloride molecular entropy | 187 J/(mol K) | 143 J/(mol K) | 69.91 J/(mol K) | 223 J/(mol K) | 83 J/(mol K) total entropy | 1122 J/(mol K) | 143 J/(mol K) | 209.7 J/(mol K) | 669 J/(mol K) | 83 J/(mol K) | S_initial = 1265 J/(mol K) | | S_final = 961.7 J/(mol K) | | ΔS_rxn^0 | 961.7 J/(mol K) - 1265 J/(mol K) = -303.3 J/(mol K) (exoentropic) | | | |

Construct the equilibrium constant, K, expression for: HCl + KClO_3 ⟶ H_2O + Cl_2 + KCl 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: 6 HCl + KClO_3 ⟶ 3 H_2O + 3 Cl_2 + KCl 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 HCl | 6 | -6 KClO_3 | 1 | -1 H_2O | 3 | 3 Cl_2 | 3 | 3 KCl | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HCl | 6 | -6 | ([HCl])^(-6) KClO_3 | 1 | -1 | ([KClO3])^(-1) H_2O | 3 | 3 | ([H2O])^3 Cl_2 | 3 | 3 | ([Cl2])^3 KCl | 1 | 1 | [KCl] 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 = ([HCl])^(-6) ([KClO3])^(-1) ([H2O])^3 ([Cl2])^3 [KCl] = (([H2O])^3 ([Cl2])^3 [KCl])/(([HCl])^6 [KClO3])

Construct the rate of reaction expression for: HCl + KClO_3 ⟶ H_2O + Cl_2 + KCl 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: 6 HCl + KClO_3 ⟶ 3 H_2O + 3 Cl_2 + KCl 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 HCl | 6 | -6 KClO_3 | 1 | -1 H_2O | 3 | 3 Cl_2 | 3 | 3 KCl | 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 HCl | 6 | -6 | -1/6 (Δ[HCl])/(Δt) KClO_3 | 1 | -1 | -(Δ[KClO3])/(Δt) H_2O | 3 | 3 | 1/3 (Δ[H2O])/(Δt) Cl_2 | 3 | 3 | 1/3 (Δ[Cl2])/(Δt) KCl | 1 | 1 | (Δ[KCl])/(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 = -1/6 (Δ[HCl])/(Δt) = -(Δ[KClO3])/(Δt) = 1/3 (Δ[H2O])/(Δt) = 1/3 (Δ[Cl2])/(Δt) = (Δ[KCl])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen chloride | potassium chlorate | water | chlorine | potassium chloride formula | HCl | KClO_3 | H_2O | Cl_2 | KCl Hill formula | ClH | ClKO_3 | H_2O | Cl_2 | ClK name | hydrogen chloride | potassium chlorate | water | chlorine | potassium chloride IUPAC name | hydrogen chloride | potassium chlorate | water | molecular chlorine | potassium chloride

| hydrogen chloride | potassium chlorate | water | chlorine | potassium chloride molar mass | 36.46 g/mol | 122.5 g/mol | 18.015 g/mol | 70.9 g/mol | 74.55 g/mol phase | gas (at STP) | solid (at STP) | liquid (at STP) | gas (at STP) | solid (at STP) melting point | -114.17 °C | 356 °C | 0 °C | -101 °C | 770 °C boiling point | -85 °C | | 99.9839 °C | -34 °C | 1420 °C density | 0.00149 g/cm^3 (at 25 °C) | 2.34 g/cm^3 | 1 g/cm^3 | 0.003214 g/cm^3 (at 0 °C) | 1.98 g/cm^3 solubility in water | miscible | soluble | | | soluble surface tension | | | 0.0728 N/m | | dynamic viscosity | | | 8.9×10^-4 Pa s (at 25 °C) | | odor | | | odorless | | odorless