Si + F2 = SiF4

Si (silicon) + F_2 (fluorine) ⟶ SiF_4 (silicon tetrafluoride)

Balance the chemical equation algebraically: Si + F_2 ⟶ SiF_4 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Si + c_2 F_2 ⟶ c_3 SiF_4 Set the number of atoms in the reactants equal to the number of atoms in the products for Si and F: Si: | c_1 = c_3 F: | 2 c_2 = 4 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 = 2 c_3 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | Si + 2 F_2 ⟶ SiF_4

+ ⟶

silicon + fluorine ⟶ silicon tetrafluoride

Construct the equilibrium constant, K, expression for: Si + F_2 ⟶ SiF_4 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: Si + 2 F_2 ⟶ SiF_4 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 Si | 1 | -1 F_2 | 2 | -2 SiF_4 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Si | 1 | -1 | ([Si])^(-1) F_2 | 2 | -2 | ([F2])^(-2) SiF_4 | 1 | 1 | [SiF4] 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 = ([Si])^(-1) ([F2])^(-2) [SiF4] = ([SiF4])/([Si] ([F2])^2)

Construct the rate of reaction expression for: Si + F_2 ⟶ SiF_4 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: Si + 2 F_2 ⟶ SiF_4 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 Si | 1 | -1 F_2 | 2 | -2 SiF_4 | 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 Si | 1 | -1 | -(Δ[Si])/(Δt) F_2 | 2 | -2 | -1/2 (Δ[F2])/(Δt) SiF_4 | 1 | 1 | (Δ[SiF4])/(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[Si])/(Δt) = -1/2 (Δ[F2])/(Δt) = (Δ[SiF4])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| silicon | fluorine | silicon tetrafluoride formula | Si | F_2 | SiF_4 Hill formula | Si | F_2 | F_4Si name | silicon | fluorine | silicon tetrafluoride IUPAC name | silicon | molecular fluorine | tetrafluorosilane

| silicon | fluorine | silicon tetrafluoride molar mass | 28.085 g/mol | 37.996806326 g/mol | 104.079 g/mol phase | solid (at STP) | gas (at STP) | gas (at STP) melting point | 1410 °C | -219.6 °C | -90.2 °C boiling point | 2355 °C | -188.12 °C | -86 °C density | 2.33 g/cm^3 | 0.001696 g/cm^3 (at 0 °C) | 0.004254 g/cm^3 (at 25 °C) solubility in water | insoluble | reacts | decomposes dynamic viscosity | | 2.344×10^-5 Pa s (at 25 °C) |