H2O + SO2 + H2Se = H2SO4 + S + Se

H_2O (water) + SO_2 (sulfur dioxide) + SeH_2 (hydrogen selenide) ⟶ H_2SO_4 (sulfuric acid) + S (mixed sulfur) + Se (gray selenium)

Balance the chemical equation algebraically: H_2O + SO_2 + SeH_2 ⟶ H_2SO_4 + S + Se Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O + c_2 SO_2 + c_3 SeH_2 ⟶ c_4 H_2SO_4 + c_5 S + c_6 Se Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, S and Se: H: | 2 c_1 + 2 c_3 = 2 c_4 O: | c_1 + 2 c_2 = 4 c_4 S: | c_2 = c_4 + c_5 Se: | c_3 = c_6 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_2 = (3 c_1)/2 + 2 c_3 = 1 c_4 = c_1 + 1 c_5 = c_1/2 + 1 c_6 = 1 The resulting system of equations is still underdetermined, so an additional coefficient must be set arbitrarily. Set c_1 = 2 and solve for the remaining coefficients: c_1 = 2 c_2 = 5 c_3 = 1 c_4 = 3 c_5 = 2 c_6 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 H_2O + 5 SO_2 + SeH_2 ⟶ 3 H_2SO_4 + 2 S + Se

+ + ⟶ + +

water + sulfur dioxide + hydrogen selenide ⟶ sulfuric acid + mixed sulfur + gray selenium

Construct the equilibrium constant, K, expression for: H_2O + SO_2 + SeH_2 ⟶ H_2SO_4 + S + Se 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: 2 H_2O + 5 SO_2 + SeH_2 ⟶ 3 H_2SO_4 + 2 S + Se 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 | 2 | -2 SO_2 | 5 | -5 SeH_2 | 1 | -1 H_2SO_4 | 3 | 3 S | 2 | 2 Se | 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 | 2 | -2 | ([H2O])^(-2) SO_2 | 5 | -5 | ([SO2])^(-5) SeH_2 | 1 | -1 | ([SeH2])^(-1) H_2SO_4 | 3 | 3 | ([H2SO4])^3 S | 2 | 2 | ([S])^2 Se | 1 | 1 | [Se] 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])^(-2) ([SO2])^(-5) ([SeH2])^(-1) ([H2SO4])^3 ([S])^2 [Se] = (([H2SO4])^3 ([S])^2 [Se])/(([H2O])^2 ([SO2])^5 [SeH2])

Construct the rate of reaction expression for: H_2O + SO_2 + SeH_2 ⟶ H_2SO_4 + S + Se 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: 2 H_2O + 5 SO_2 + SeH_2 ⟶ 3 H_2SO_4 + 2 S + Se 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 | 2 | -2 SO_2 | 5 | -5 SeH_2 | 1 | -1 H_2SO_4 | 3 | 3 S | 2 | 2 Se | 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 | 2 | -2 | -1/2 (Δ[H2O])/(Δt) SO_2 | 5 | -5 | -1/5 (Δ[SO2])/(Δt) SeH_2 | 1 | -1 | -(Δ[SeH2])/(Δt) H_2SO_4 | 3 | 3 | 1/3 (Δ[H2SO4])/(Δt) S | 2 | 2 | 1/2 (Δ[S])/(Δt) Se | 1 | 1 | (Δ[Se])/(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 = -1/2 (Δ[H2O])/(Δt) = -1/5 (Δ[SO2])/(Δt) = -(Δ[SeH2])/(Δt) = 1/3 (Δ[H2SO4])/(Δt) = 1/2 (Δ[S])/(Δt) = (Δ[Se])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| water | sulfur dioxide | hydrogen selenide | sulfuric acid | mixed sulfur | gray selenium formula | H_2O | SO_2 | SeH_2 | H_2SO_4 | S | Se Hill formula | H_2O | O_2S | H_2Se | H_2O_4S | S | Se name | water | sulfur dioxide | hydrogen selenide | sulfuric acid | mixed sulfur | gray selenium IUPAC name | water | sulfur dioxide | hydrogen selenide | sulfuric acid | sulfur | selenium