I2 + C2H4 = C2H4I2

I_2 iodine + CH_2=CH_2 ethylene ⟶ ICH_2CH_2I 1, 2-diiodoethane

Balance the chemical equation algebraically: I_2 + CH_2=CH_2 ⟶ ICH_2CH_2I Add stoichiometric coefficients, c_i, to the reactants and products: c_1 I_2 + c_2 CH_2=CH_2 ⟶ c_3 ICH_2CH_2I Set the number of atoms in the reactants equal to the number of atoms in the products for I, C and H: I: | 2 c_1 = 2 c_3 C: | 2 c_2 = 2 c_3 H: | 4 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 = 1 c_3 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | I_2 + CH_2=CH_2 ⟶ ICH_2CH_2I

+ ⟶

iodine + ethylene ⟶ 1, 2-diiodoethane

| iodine | ethylene | 1, 2-diiodoethane molecular enthalpy | 0 kJ/mol | 52.4 kJ/mol | 9.3 kJ/mol total enthalpy | 0 kJ/mol | 52.4 kJ/mol | 9.3 kJ/mol | H_initial = 52.4 kJ/mol | | H_final = 9.3 kJ/mol ΔH_rxn^0 | 9.3 kJ/mol - 52.4 kJ/mol = -43.1 kJ/mol (exothermic) | |

Construct the equilibrium constant, K, expression for: I_2 + CH_2=CH_2 ⟶ ICH_2CH_2I 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: I_2 + CH_2=CH_2 ⟶ ICH_2CH_2I 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 I_2 | 1 | -1 CH_2=CH_2 | 1 | -1 ICH_2CH_2I | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression I_2 | 1 | -1 | ([I2])^(-1) CH_2=CH_2 | 1 | -1 | ([CH2=CH2])^(-1) ICH_2CH_2I | 1 | 1 | [ICH2CH2I] 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 = ([I2])^(-1) ([CH2=CH2])^(-1) [ICH2CH2I] = ([ICH2CH2I])/([I2] [CH2=CH2])

Construct the rate of reaction expression for: I_2 + CH_2=CH_2 ⟶ ICH_2CH_2I 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: I_2 + CH_2=CH_2 ⟶ ICH_2CH_2I 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 I_2 | 1 | -1 CH_2=CH_2 | 1 | -1 ICH_2CH_2I | 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 I_2 | 1 | -1 | -(Δ[I2])/(Δt) CH_2=CH_2 | 1 | -1 | -(Δ[CH2=CH2])/(Δt) ICH_2CH_2I | 1 | 1 | (Δ[ICH2CH2I])/(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[I2])/(Δt) = -(Δ[CH2=CH2])/(Δt) = (Δ[ICH2CH2I])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| iodine | ethylene | 1, 2-diiodoethane formula | I_2 | CH_2=CH_2 | ICH_2CH_2I Hill formula | I_2 | C_2H_4 | C_2H_4I_2 name | iodine | ethylene | 1, 2-diiodoethane IUPAC name | molecular iodine | ethylene | 1, 2-diiodoethane

| iodine | ethylene | 1, 2-diiodoethane molar mass | 253.80894 g/mol | 28.054 g/mol | 281.863 g/mol phase | solid (at STP) | gas (at STP) | solid (at STP) melting point | 113 °C | -169 °C | 81 °C boiling point | 184 °C | -104 °C | 206 °C density | 4.94 g/cm^3 | 1.153 g/cm^3 (at 25 °C) | 2.132 g/cm^3 solubility in water | | insoluble | insoluble surface tension | | 0.0181 N/m | dynamic viscosity | 0.00227 Pa s (at 116 °C) | 1.034×10^-5 Pa s (at 25 °C) |