HCl + AsH3 = H2 + AsCl3

HCl hydrogen chloride + AsH_3 arsine ⟶ H_2 hydrogen + AsCl_3 arsenic trichloride

Balance the chemical equation algebraically: HCl + AsH_3 ⟶ H_2 + AsCl_3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HCl + c_2 AsH_3 ⟶ c_3 H_2 + c_4 AsCl_3 Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, H and As: Cl: | c_1 = 3 c_4 H: | c_1 + 3 c_2 = 2 c_3 As: | 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 = 3 c_2 = 1 c_3 = 3 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 HCl + AsH_3 ⟶ 3 H_2 + AsCl_3

+ ⟶ +

hydrogen chloride + arsine ⟶ hydrogen + arsenic trichloride

| hydrogen chloride | arsine | hydrogen | arsenic trichloride molecular free energy | -95.3 kJ/mol | 68.9 kJ/mol | 0 kJ/mol | -259.4 kJ/mol total free energy | -285.9 kJ/mol | 68.9 kJ/mol | 0 kJ/mol | -259.4 kJ/mol | G_initial = -217 kJ/mol | | G_final = -259.4 kJ/mol | ΔG_rxn^0 | -259.4 kJ/mol - -217 kJ/mol = -42.4 kJ/mol (exergonic) | | |

Construct the equilibrium constant, K, expression for: HCl + AsH_3 ⟶ H_2 + AsCl_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 HCl + AsH_3 ⟶ 3 H_2 + AsCl_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 HCl | 3 | -3 AsH_3 | 1 | -1 H_2 | 3 | 3 AsCl_3 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HCl | 3 | -3 | ([HCl])^(-3) AsH_3 | 1 | -1 | ([AsH3])^(-1) H_2 | 3 | 3 | ([H2])^3 AsCl_3 | 1 | 1 | [AsCl3] 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])^(-3) ([AsH3])^(-1) ([H2])^3 [AsCl3] = (([H2])^3 [AsCl3])/(([HCl])^3 [AsH3])

Construct the rate of reaction expression for: HCl + AsH_3 ⟶ H_2 + AsCl_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 HCl + AsH_3 ⟶ 3 H_2 + AsCl_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 HCl | 3 | -3 AsH_3 | 1 | -1 H_2 | 3 | 3 AsCl_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 HCl | 3 | -3 | -1/3 (Δ[HCl])/(Δt) AsH_3 | 1 | -1 | -(Δ[AsH3])/(Δt) H_2 | 3 | 3 | 1/3 (Δ[H2])/(Δt) AsCl_3 | 1 | 1 | (Δ[AsCl3])/(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[HCl])/(Δt) = -(Δ[AsH3])/(Δt) = 1/3 (Δ[H2])/(Δt) = (Δ[AsCl3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen chloride | arsine | hydrogen | arsenic trichloride formula | HCl | AsH_3 | H_2 | AsCl_3 Hill formula | ClH | AsH_3 | H_2 | AsCl_3 name | hydrogen chloride | arsine | hydrogen | arsenic trichloride IUPAC name | hydrogen chloride | arsane | molecular hydrogen | trichloroarsane