Cl2 + S = SCl6

Cl_2 chlorine + S mixed sulfur ⟶ SCl6

Balance the chemical equation algebraically: Cl_2 + S ⟶ SCl6 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Cl_2 + c_2 S ⟶ c_3 SCl6 Set the number of atoms in the reactants equal to the number of atoms in the products for Cl and S: Cl: | 2 c_1 = 6 c_3 S: | 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 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 Cl_2 + S ⟶ SCl6

+ ⟶ SCl6

chlorine + mixed sulfur ⟶ SCl6

Construct the equilibrium constant, K, expression for: Cl_2 + S ⟶ SCl6 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 Cl_2 + S ⟶ SCl6 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 Cl_2 | 3 | -3 S | 1 | -1 SCl6 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Cl_2 | 3 | -3 | ([Cl2])^(-3) S | 1 | -1 | ([S])^(-1) SCl6 | 1 | 1 | [SCl6] 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 = ([Cl2])^(-3) ([S])^(-1) [SCl6] = ([SCl6])/(([Cl2])^3 [S])

Construct the rate of reaction expression for: Cl_2 + S ⟶ SCl6 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 Cl_2 + S ⟶ SCl6 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 Cl_2 | 3 | -3 S | 1 | -1 SCl6 | 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 Cl_2 | 3 | -3 | -1/3 (Δ[Cl2])/(Δt) S | 1 | -1 | -(Δ[S])/(Δt) SCl6 | 1 | 1 | (Δ[SCl6])/(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[Cl2])/(Δt) = -(Δ[S])/(Δt) = (Δ[SCl6])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| chlorine | mixed sulfur | SCl6 formula | Cl_2 | S | SCl6 Hill formula | Cl_2 | S | Cl6S name | chlorine | mixed sulfur | IUPAC name | molecular chlorine | sulfur |

| chlorine | mixed sulfur | SCl6 molar mass | 70.9 g/mol | 32.06 g/mol | 244.8 g/mol phase | gas (at STP) | solid (at STP) | melting point | -101 °C | 112.8 °C | boiling point | -34 °C | 444.7 °C | density | 0.003214 g/cm^3 (at 0 °C) | 2.07 g/cm^3 |