BCl2 = B2Cl4

BCl2 ⟶ B_2Cl_4 tetrachloradiborane

Balance the chemical equation algebraically: BCl2 ⟶ B_2Cl_4 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 BCl2 ⟶ c_2 B_2Cl_4 Set the number of atoms in the reactants equal to the number of atoms in the products for B and Cl: B: | c_1 = 2 c_2 Cl: | 2 c_1 = 4 c_2 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 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 BCl2 ⟶ B_2Cl_4

BCl2 ⟶

BCl2 ⟶ tetrachloradiborane

Construct the equilibrium constant, K, expression for: BCl2 ⟶ B_2Cl_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: 2 BCl2 ⟶ B_2Cl_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 BCl2 | 2 | -2 B_2Cl_4 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression BCl2 | 2 | -2 | ([BCl2])^(-2) B_2Cl_4 | 1 | 1 | [B2Cl4] 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 = ([BCl2])^(-2) [B2Cl4] = ([B2Cl4])/([BCl2])^2

Construct the rate of reaction expression for: BCl2 ⟶ B_2Cl_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: 2 BCl2 ⟶ B_2Cl_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 BCl2 | 2 | -2 B_2Cl_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 BCl2 | 2 | -2 | -1/2 (Δ[BCl2])/(Δt) B_2Cl_4 | 1 | 1 | (Δ[B2Cl4])/(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[BCl2])/(Δt) = (Δ[B2Cl4])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| BCl2 | tetrachloradiborane formula | BCl2 | B_2Cl_4 name | | tetrachloradiborane IUPAC name | | dichloro(dichloroboranyl)borane

| BCl2 | tetrachloradiborane molar mass | 81.71 g/mol | 163.4 g/mol