H2S + HOCl = H2O + HCl + S

H_2S hydrogen sulfide + HOCl hypochlorous acid ⟶ H_2O water + HCl hydrogen chloride + S mixed sulfur

Balance the chemical equation algebraically: H_2S + HOCl ⟶ H_2O + HCl + S Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2S + c_2 HOCl ⟶ c_3 H_2O + c_4 HCl + c_5 S Set the number of atoms in the reactants equal to the number of atoms in the products for H, S, Cl and O: H: | 2 c_1 + c_2 = 2 c_3 + c_4 S: | c_1 = c_5 Cl: | c_2 = c_4 O: | 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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 1 c_3 = 1 c_4 = 1 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | H_2S + HOCl ⟶ H_2O + HCl + S

+ ⟶ + +

hydrogen sulfide + hypochlorous acid ⟶ water + hydrogen chloride + mixed sulfur

Construct the equilibrium constant, K, expression for: H_2S + HOCl ⟶ H_2O + HCl + S 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: H_2S + HOCl ⟶ H_2O + HCl + S 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_2S | 1 | -1 HOCl | 1 | -1 H_2O | 1 | 1 HCl | 1 | 1 S | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2S | 1 | -1 | ([H2S])^(-1) HOCl | 1 | -1 | ([HOCl])^(-1) H_2O | 1 | 1 | [H2O] HCl | 1 | 1 | [HCl] S | 1 | 1 | [S] 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 = ([H2S])^(-1) ([HOCl])^(-1) [H2O] [HCl] [S] = ([H2O] [HCl] [S])/([H2S] [HOCl])

Construct the rate of reaction expression for: H_2S + HOCl ⟶ H_2O + HCl + S 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: H_2S + HOCl ⟶ H_2O + HCl + S 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_2S | 1 | -1 HOCl | 1 | -1 H_2O | 1 | 1 HCl | 1 | 1 S | 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_2S | 1 | -1 | -(Δ[H2S])/(Δt) HOCl | 1 | -1 | -(Δ[HOCl])/(Δt) H_2O | 1 | 1 | (Δ[H2O])/(Δt) HCl | 1 | 1 | (Δ[HCl])/(Δt) S | 1 | 1 | (Δ[S])/(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 = -(Δ[H2S])/(Δt) = -(Δ[HOCl])/(Δt) = (Δ[H2O])/(Δt) = (Δ[HCl])/(Δt) = (Δ[S])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen sulfide | hypochlorous acid | water | hydrogen chloride | mixed sulfur formula | H_2S | HOCl | H_2O | HCl | S Hill formula | H_2S | ClHO | H_2O | ClH | S name | hydrogen sulfide | hypochlorous acid | water | hydrogen chloride | mixed sulfur IUPAC name | hydrogen sulfide | hypochlorous acid | water | hydrogen chloride | sulfur