S + F2 = SF6

S (mixed sulfur) + F_2 (fluorine) ⟶ SF_6 (sulfur hexafluoride)

Balance the chemical equation algebraically: S + F_2 ⟶ SF_6 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 S + c_2 F_2 ⟶ c_3 SF_6 Set the number of atoms in the reactants equal to the number of atoms in the products for S and F: S: | c_1 = c_3 F: | 2 c_2 = 6 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 = 3 c_3 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | S + 3 F_2 ⟶ SF_6

+ ⟶

mixed sulfur + fluorine ⟶ sulfur hexafluoride

Construct the equilibrium constant, K, expression for: S + F_2 ⟶ SF_6 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: S + 3 F_2 ⟶ SF_6 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 S | 1 | -1 F_2 | 3 | -3 SF_6 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression S | 1 | -1 | ([S])^(-1) F_2 | 3 | -3 | ([F2])^(-3) SF_6 | 1 | 1 | [SF6] 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 = ([S])^(-1) ([F2])^(-3) [SF6] = ([SF6])/([S] ([F2])^3)

Construct the rate of reaction expression for: S + F_2 ⟶ SF_6 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: S + 3 F_2 ⟶ SF_6 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 S | 1 | -1 F_2 | 3 | -3 SF_6 | 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 S | 1 | -1 | -(Δ[S])/(Δt) F_2 | 3 | -3 | -1/3 (Δ[F2])/(Δt) SF_6 | 1 | 1 | (Δ[SF6])/(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[S])/(Δt) = -1/3 (Δ[F2])/(Δt) = (Δ[SF6])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| mixed sulfur | fluorine | sulfur hexafluoride formula | S | F_2 | SF_6 Hill formula | S | F_2 | F_6S name | mixed sulfur | fluorine | sulfur hexafluoride IUPAC name | sulfur | molecular fluorine |

| mixed sulfur | fluorine | sulfur hexafluoride molar mass | 32.06 g/mol | 37.996806326 g/mol | 146.05 g/mol phase | solid (at STP) | gas (at STP) | gas (at STP) melting point | 112.8 °C | -219.6 °C | -49.596 °C boiling point | 444.7 °C | -188.12 °C | -63.8 °C density | 2.07 g/cm^3 | 0.001696 g/cm^3 (at 0 °C) | 0.00597 g/cm^3 (at 50 °C) solubility in water | | reacts | dynamic viscosity | | 2.344×10^-5 Pa s (at 25 °C) | 3.7204×10^-5 Pa s (at 627 °C) odor | | | odorless