H2 + AlCl3 = HCl + Al

H_2 hydrogen + AlCl_3 aluminum chloride ⟶ HCl hydrogen chloride + Al aluminum

Balance the chemical equation algebraically: H_2 + AlCl_3 ⟶ HCl + Al Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2 + c_2 AlCl_3 ⟶ c_3 HCl + c_4 Al Set the number of atoms in the reactants equal to the number of atoms in the products for H, Al and Cl: H: | 2 c_1 = c_3 Al: | c_2 = c_4 Cl: | 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 = 3/2 c_2 = 1 c_3 = 3 c_4 = 1 Multiply by the least common denominator, 2, to eliminate fractional coefficients: c_1 = 3 c_2 = 2 c_3 = 6 c_4 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 H_2 + 2 AlCl_3 ⟶ 6 HCl + 2 Al

+ ⟶ +

hydrogen + aluminum chloride ⟶ hydrogen chloride + aluminum

| hydrogen | aluminum chloride | hydrogen chloride | aluminum molecular enthalpy | 0 kJ/mol | -704.2 kJ/mol | -92.3 kJ/mol | 0 kJ/mol total enthalpy | 0 kJ/mol | -1408 kJ/mol | -553.8 kJ/mol | 0 kJ/mol | H_initial = -1408 kJ/mol | | H_final = -553.8 kJ/mol | ΔH_rxn^0 | -553.8 kJ/mol - -1408 kJ/mol = 854.6 kJ/mol (endothermic) | | |

| hydrogen | aluminum chloride | hydrogen chloride | aluminum molecular entropy | 115 J/(mol K) | 111 J/(mol K) | 187 J/(mol K) | 28.3 J/(mol K) total entropy | 345 J/(mol K) | 222 J/(mol K) | 1122 J/(mol K) | 56.6 J/(mol K) | S_initial = 567 J/(mol K) | | S_final = 1179 J/(mol K) | ΔS_rxn^0 | 1179 J/(mol K) - 567 J/(mol K) = 611.6 J/(mol K) (endoentropic) | | |

Construct the equilibrium constant, K, expression for: H_2 + AlCl_3 ⟶ HCl + Al 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_2 + 2 AlCl_3 ⟶ 6 HCl + 2 Al 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_2 | 3 | -3 AlCl_3 | 2 | -2 HCl | 6 | 6 Al | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2 | 3 | -3 | ([H2])^(-3) AlCl_3 | 2 | -2 | ([AlCl3])^(-2) HCl | 6 | 6 | ([HCl])^6 Al | 2 | 2 | ([Al])^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 = ([H2])^(-3) ([AlCl3])^(-2) ([HCl])^6 ([Al])^2 = (([HCl])^6 ([Al])^2)/(([H2])^3 ([AlCl3])^2)

Construct the rate of reaction expression for: H_2 + AlCl_3 ⟶ HCl + Al 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_2 + 2 AlCl_3 ⟶ 6 HCl + 2 Al 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_2 | 3 | -3 AlCl_3 | 2 | -2 HCl | 6 | 6 Al | 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_2 | 3 | -3 | -1/3 (Δ[H2])/(Δt) AlCl_3 | 2 | -2 | -1/2 (Δ[AlCl3])/(Δt) HCl | 6 | 6 | 1/6 (Δ[HCl])/(Δt) Al | 2 | 2 | 1/2 (Δ[Al])/(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[H2])/(Δt) = -1/2 (Δ[AlCl3])/(Δt) = 1/6 (Δ[HCl])/(Δt) = 1/2 (Δ[Al])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen | aluminum chloride | hydrogen chloride | aluminum formula | H_2 | AlCl_3 | HCl | Al Hill formula | H_2 | AlCl_3 | ClH | Al name | hydrogen | aluminum chloride | hydrogen chloride | aluminum IUPAC name | molecular hydrogen | trichloroalumane | hydrogen chloride | aluminum

| hydrogen | aluminum chloride | hydrogen chloride | aluminum molar mass | 2.016 g/mol | 133.3 g/mol | 36.46 g/mol | 26.9815385 g/mol phase | gas (at STP) | solid (at STP) | gas (at STP) | solid (at STP) melting point | -259.2 °C | 190 °C | -114.17 °C | 660.4 °C boiling point | -252.8 °C | | -85 °C | 2460 °C density | 8.99×10^-5 g/cm^3 (at 0 °C) | | 0.00149 g/cm^3 (at 25 °C) | 2.7 g/cm^3 solubility in water | | | miscible | insoluble surface tension | | | | 0.817 N/m dynamic viscosity | 8.9×10^-6 Pa s (at 25 °C) | | | 1.5×10^-4 Pa s (at 760 °C) odor | odorless | | | odorless