CuI2 = I2 + CuI

CuI2 ⟶ I_2 (iodine) + CuI (cuprous iodide)

Balance the chemical equation algebraically: CuI2 ⟶ I_2 + CuI Add stoichiometric coefficients, c_i, to the reactants and products: c_1 CuI2 ⟶ c_2 I_2 + c_3 CuI Set the number of atoms in the reactants equal to the number of atoms in the products for Cu and I: Cu: | c_1 = c_3 I: | 2 c_1 = 2 c_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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 1 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 CuI2 ⟶ I_2 + 2 CuI

CuI2 ⟶ +

CuI2 ⟶ iodine + cuprous iodide

Construct the equilibrium constant, K, expression for: CuI2 ⟶ I_2 + CuI 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 CuI2 ⟶ I_2 + 2 CuI 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 CuI2 | 2 | -2 I_2 | 1 | 1 CuI | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression CuI2 | 2 | -2 | ([CuI2])^(-2) I_2 | 1 | 1 | [I2] CuI | 2 | 2 | ([CuI])^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 = ([CuI2])^(-2) [I2] ([CuI])^2 = ([I2] ([CuI])^2)/([CuI2])^2

Construct the rate of reaction expression for: CuI2 ⟶ I_2 + CuI 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 CuI2 ⟶ I_2 + 2 CuI 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 CuI2 | 2 | -2 I_2 | 1 | 1 CuI | 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 CuI2 | 2 | -2 | -1/2 (Δ[CuI2])/(Δt) I_2 | 1 | 1 | (Δ[I2])/(Δt) CuI | 2 | 2 | 1/2 (Δ[CuI])/(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[CuI2])/(Δt) = (Δ[I2])/(Δt) = 1/2 (Δ[CuI])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| CuI2 | iodine | cuprous iodide formula | CuI2 | I_2 | CuI name | | iodine | cuprous iodide IUPAC name | | molecular iodine | cuprous iodide

| CuI2 | iodine | cuprous iodide molar mass | 317.355 g/mol | 253.80894 g/mol | 190.45 g/mol phase | | solid (at STP) | solid (at STP) melting point | | 113 °C | 605 °C boiling point | | 184 °C | 1290 °C density | | 4.94 g/cm^3 | 5.62 g/cm^3 solubility in water | | | insoluble dynamic viscosity | | 0.00227 Pa s (at 116 °C) |