O2 + I2 = I2O7

O_2 oxygen + I_2 iodine ⟶ I2O7

Balance the chemical equation algebraically: O_2 + I_2 ⟶ I2O7 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 O_2 + c_2 I_2 ⟶ c_3 I2O7 Set the number of atoms in the reactants equal to the number of atoms in the products for O and I: O: | 2 c_1 = 7 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 7/2 c_2 = 1 c_3 = 1 Multiply by the least common denominator, 2, to eliminate fractional coefficients: c_1 = 7 c_2 = 2 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 7 O_2 + 2 I_2 ⟶ 2 I2O7

+ ⟶ I2O7

oxygen + iodine ⟶ I2O7

Construct the equilibrium constant, K, expression for: O_2 + I_2 ⟶ I2O7 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: 7 O_2 + 2 I_2 ⟶ 2 I2O7 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 O_2 | 7 | -7 I_2 | 2 | -2 I2O7 | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression O_2 | 7 | -7 | ([O2])^(-7) I_2 | 2 | -2 | ([I2])^(-2) I2O7 | 2 | 2 | ([I2O7])^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 = ([O2])^(-7) ([I2])^(-2) ([I2O7])^2 = ([I2O7])^2/(([O2])^7 ([I2])^2)

Construct the rate of reaction expression for: O_2 + I_2 ⟶ I2O7 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: 7 O_2 + 2 I_2 ⟶ 2 I2O7 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 O_2 | 7 | -7 I_2 | 2 | -2 I2O7 | 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 O_2 | 7 | -7 | -1/7 (Δ[O2])/(Δt) I_2 | 2 | -2 | -1/2 (Δ[I2])/(Δt) I2O7 | 2 | 2 | 1/2 (Δ[I2O7])/(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 = -1/7 (Δ[O2])/(Δt) = -1/2 (Δ[I2])/(Δt) = 1/2 (Δ[I2O7])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| oxygen | iodine | I2O7 formula | O_2 | I_2 | I2O7 name | oxygen | iodine | IUPAC name | molecular oxygen | molecular iodine |

| oxygen | iodine | I2O7 molar mass | 31.998 g/mol | 253.80894 g/mol | 365.8 g/mol phase | gas (at STP) | solid (at STP) | melting point | -218 °C | 113 °C | boiling point | -183 °C | 184 °C | density | 0.001429 g/cm^3 (at 0 °C) | 4.94 g/cm^3 | surface tension | 0.01347 N/m | | dynamic viscosity | 2.055×10^-5 Pa s (at 25 °C) | 0.00227 Pa s (at 116 °C) | odor | odorless | |