H2 + Au2S3 = H2S + Au

H_2 hydrogen + Au_2S_3 gold(III) sulfide ⟶ H_2S hydrogen sulfide + Au gold

Balance the chemical equation algebraically: H_2 + Au_2S_3 ⟶ H_2S + Au Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2 + c_2 Au_2S_3 ⟶ c_3 H_2S + c_4 Au Set the number of atoms in the reactants equal to the number of atoms in the products for H, Au and S: H: | 2 c_1 = 2 c_3 Au: | 2 c_2 = c_4 S: | 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 c_2 = 1 c_3 = 3 c_4 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 H_2 + Au_2S_3 ⟶ 3 H_2S + 2 Au

+ ⟶ +

hydrogen + gold(III) sulfide ⟶ hydrogen sulfide + gold

Construct the equilibrium constant, K, expression for: H_2 + Au_2S_3 ⟶ H_2S + Au 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 + Au_2S_3 ⟶ 3 H_2S + 2 Au 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 Au_2S_3 | 1 | -1 H_2S | 3 | 3 Au | 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) Au_2S_3 | 1 | -1 | ([Au2S3])^(-1) H_2S | 3 | 3 | ([H2S])^3 Au | 2 | 2 | ([Au])^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) ([Au2S3])^(-1) ([H2S])^3 ([Au])^2 = (([H2S])^3 ([Au])^2)/(([H2])^3 [Au2S3])

Construct the rate of reaction expression for: H_2 + Au_2S_3 ⟶ H_2S + Au 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 + Au_2S_3 ⟶ 3 H_2S + 2 Au 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 Au_2S_3 | 1 | -1 H_2S | 3 | 3 Au | 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) Au_2S_3 | 1 | -1 | -(Δ[Au2S3])/(Δt) H_2S | 3 | 3 | 1/3 (Δ[H2S])/(Δt) Au | 2 | 2 | 1/2 (Δ[Au])/(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) = -(Δ[Au2S3])/(Δt) = 1/3 (Δ[H2S])/(Δt) = 1/2 (Δ[Au])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen | gold(III) sulfide | hydrogen sulfide | gold formula | H_2 | Au_2S_3 | H_2S | Au name | hydrogen | gold(III) sulfide | hydrogen sulfide | gold IUPAC name | molecular hydrogen | gold(+3) cation trisulfide | hydrogen sulfide | gold

| hydrogen | gold(III) sulfide | hydrogen sulfide | gold molar mass | 2.016 g/mol | 490.11 g/mol | 34.08 g/mol | 196.966569 g/mol phase | gas (at STP) | solid (at STP) | gas (at STP) | solid (at STP) melting point | -259.2 °C | 200 °C | -85 °C | 1063 °C boiling point | -252.8 °C | | -60 °C | 2856 °C density | 8.99×10^-5 g/cm^3 (at 0 °C) | 8.75 g/cm^3 | 0.001393 g/cm^3 (at 25 °C) | 19.3 g/cm^3 solubility in water | | insoluble | | insoluble dynamic viscosity | 8.9×10^-6 Pa s (at 25 °C) | | 1.239×10^-5 Pa s (at 25 °C) | odor | odorless | | |