Zn + SiCl4 = ZnCl2 + Si

Zn zinc + SiCl_4 silicon tetrachloride ⟶ ZnCl_2 zinc chloride + Si silicon

Balance the chemical equation algebraically: Zn + SiCl_4 ⟶ ZnCl_2 + Si Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Zn + c_2 SiCl_4 ⟶ c_3 ZnCl_2 + c_4 Si Set the number of atoms in the reactants equal to the number of atoms in the products for Zn, Cl and Si: Zn: | c_1 = c_3 Cl: | 4 c_2 = 2 c_3 Si: | c_2 = c_4 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 = 2 c_2 = 1 c_3 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 Zn + SiCl_4 ⟶ 2 ZnCl_2 + Si

+ ⟶ +

zinc + silicon tetrachloride ⟶ zinc chloride + silicon

Construct the equilibrium constant, K, expression for: Zn + SiCl_4 ⟶ ZnCl_2 + Si 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 Zn + SiCl_4 ⟶ 2 ZnCl_2 + Si 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 Zn | 2 | -2 SiCl_4 | 1 | -1 ZnCl_2 | 2 | 2 Si | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Zn | 2 | -2 | ([Zn])^(-2) SiCl_4 | 1 | -1 | ([SiCl4])^(-1) ZnCl_2 | 2 | 2 | ([ZnCl2])^2 Si | 1 | 1 | [Si] 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 = ([Zn])^(-2) ([SiCl4])^(-1) ([ZnCl2])^2 [Si] = (([ZnCl2])^2 [Si])/(([Zn])^2 [SiCl4])

Construct the rate of reaction expression for: Zn + SiCl_4 ⟶ ZnCl_2 + Si 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 Zn + SiCl_4 ⟶ 2 ZnCl_2 + Si 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 Zn | 2 | -2 SiCl_4 | 1 | -1 ZnCl_2 | 2 | 2 Si | 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 Zn | 2 | -2 | -1/2 (Δ[Zn])/(Δt) SiCl_4 | 1 | -1 | -(Δ[SiCl4])/(Δt) ZnCl_2 | 2 | 2 | 1/2 (Δ[ZnCl2])/(Δt) Si | 1 | 1 | (Δ[Si])/(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[Zn])/(Δt) = -(Δ[SiCl4])/(Δt) = 1/2 (Δ[ZnCl2])/(Δt) = (Δ[Si])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| zinc | silicon tetrachloride | zinc chloride | silicon formula | Zn | SiCl_4 | ZnCl_2 | Si Hill formula | Zn | Cl_4Si | Cl_2Zn | Si name | zinc | silicon tetrachloride | zinc chloride | silicon IUPAC name | zinc | tetrachlorosilane | zinc dichloride | silicon

| zinc | silicon tetrachloride | zinc chloride | silicon molar mass | 65.38 g/mol | 169.9 g/mol | 136.3 g/mol | 28.085 g/mol phase | solid (at STP) | liquid (at STP) | solid (at STP) | solid (at STP) melting point | 420 °C | -70 °C | 293 °C | 1410 °C boiling point | 907 °C | 57.6 °C | | 2355 °C density | 7.14 g/cm^3 | 1.483 g/cm^3 | | 2.33 g/cm^3 solubility in water | insoluble | decomposes | soluble | insoluble surface tension | | 0.0196 N/m | | dynamic viscosity | | 0.0994 Pa s (at 25 °C) | | odor | odorless | | odorless |