Cl2 + I2 = I2Cl

Cl_2 chlorine + I_2 iodine ⟶ I2Cl

Balance the chemical equation algebraically: Cl_2 + I_2 ⟶ I2Cl Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Cl_2 + c_2 I_2 ⟶ c_3 I2Cl Set the number of atoms in the reactants equal to the number of atoms in the products for Cl and I: Cl: | 2 c_1 = c_3 I: | 2 c_2 = 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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 2 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | Cl_2 + 2 I_2 ⟶ 2 I2Cl

+ ⟶ I2Cl

chlorine + iodine ⟶ I2Cl

Construct the equilibrium constant, K, expression for: Cl_2 + I_2 ⟶ I2Cl 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: Cl_2 + 2 I_2 ⟶ 2 I2Cl 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 | 1 | -1 I_2 | 2 | -2 I2Cl | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Cl_2 | 1 | -1 | ([Cl2])^(-1) I_2 | 2 | -2 | ([I2])^(-2) I2Cl | 2 | 2 | ([I2Cl])^2 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])^(-1) ([I2])^(-2) ([I2Cl])^2 = ([I2Cl])^2/([Cl2] ([I2])^2)

Construct the rate of reaction expression for: Cl_2 + I_2 ⟶ I2Cl 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: Cl_2 + 2 I_2 ⟶ 2 I2Cl 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 | 1 | -1 I_2 | 2 | -2 I2Cl | 2 | 2 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 | 1 | -1 | -(Δ[Cl2])/(Δt) I_2 | 2 | -2 | -1/2 (Δ[I2])/(Δt) I2Cl | 2 | 2 | 1/2 (Δ[I2Cl])/(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[Cl2])/(Δt) = -1/2 (Δ[I2])/(Δt) = 1/2 (Δ[I2Cl])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| chlorine | iodine | I2Cl formula | Cl_2 | I_2 | I2Cl Hill formula | Cl_2 | I_2 | ClI2 name | chlorine | iodine | IUPAC name | molecular chlorine | molecular iodine |

| chlorine | iodine | I2Cl molar mass | 70.9 g/mol | 253.80894 g/mol | 289.26 g/mol phase | gas (at STP) | solid (at STP) | melting point | -101 °C | 113 °C | boiling point | -34 °C | 184 °C | density | 0.003214 g/cm^3 (at 0 °C) | 4.94 g/cm^3 | dynamic viscosity | | 0.00227 Pa s (at 116 °C) |