Na2SO3 + NaIO3 + NaHSO3 = H2O + I2 + Na2SO4

Na_2SO_3 sodium sulfite + NaIO_3 sodium iodate + NaHSO_3 sodium bisulfite ⟶ H_2O water + I_2 iodine + Na_2SO_4 sodium sulfate

Balance the chemical equation algebraically: Na_2SO_3 + NaIO_3 + NaHSO_3 ⟶ H_2O + I_2 + Na_2SO_4 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Na_2SO_3 + c_2 NaIO_3 + c_3 NaHSO_3 ⟶ c_4 H_2O + c_5 I_2 + c_6 Na_2SO_4 Set the number of atoms in the reactants equal to the number of atoms in the products for Na, O, S, I and H: Na: | 2 c_1 + c_2 + c_3 = 2 c_6 O: | 3 c_1 + 3 c_2 + 3 c_3 = c_4 + 4 c_6 S: | c_1 + c_3 = c_6 I: | c_2 = 2 c_5 H: | c_3 = 2 c_4 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_4 = 1 and solve the system of equations for the remaining coefficients: c_1 = 3 c_2 = 2 c_3 = 2 c_4 = 1 c_5 = 1 c_6 = 5 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 Na_2SO_3 + 2 NaIO_3 + 2 NaHSO_3 ⟶ H_2O + I_2 + 5 Na_2SO_4

+ + ⟶ + +

sodium sulfite + sodium iodate + sodium bisulfite ⟶ water + iodine + sodium sulfate

Construct the equilibrium constant, K, expression for: Na_2SO_3 + NaIO_3 + NaHSO_3 ⟶ H_2O + I_2 + Na_2SO_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: 3 Na_2SO_3 + 2 NaIO_3 + 2 NaHSO_3 ⟶ H_2O + I_2 + 5 Na_2SO_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 Na_2SO_3 | 3 | -3 NaIO_3 | 2 | -2 NaHSO_3 | 2 | -2 H_2O | 1 | 1 I_2 | 1 | 1 Na_2SO_4 | 5 | 5 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Na_2SO_3 | 3 | -3 | ([Na2SO3])^(-3) NaIO_3 | 2 | -2 | ([NaIO3])^(-2) NaHSO_3 | 2 | -2 | ([NaHSO3])^(-2) H_2O | 1 | 1 | [H2O] I_2 | 1 | 1 | [I2] Na_2SO_4 | 5 | 5 | ([Na2SO4])^5 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 = ([Na2SO3])^(-3) ([NaIO3])^(-2) ([NaHSO3])^(-2) [H2O] [I2] ([Na2SO4])^5 = ([H2O] [I2] ([Na2SO4])^5)/(([Na2SO3])^3 ([NaIO3])^2 ([NaHSO3])^2)

Construct the rate of reaction expression for: Na_2SO_3 + NaIO_3 + NaHSO_3 ⟶ H_2O + I_2 + Na_2SO_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: 3 Na_2SO_3 + 2 NaIO_3 + 2 NaHSO_3 ⟶ H_2O + I_2 + 5 Na_2SO_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 Na_2SO_3 | 3 | -3 NaIO_3 | 2 | -2 NaHSO_3 | 2 | -2 H_2O | 1 | 1 I_2 | 1 | 1 Na_2SO_4 | 5 | 5 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 Na_2SO_3 | 3 | -3 | -1/3 (Δ[Na2SO3])/(Δt) NaIO_3 | 2 | -2 | -1/2 (Δ[NaIO3])/(Δt) NaHSO_3 | 2 | -2 | -1/2 (Δ[NaHSO3])/(Δt) H_2O | 1 | 1 | (Δ[H2O])/(Δt) I_2 | 1 | 1 | (Δ[I2])/(Δt) Na_2SO_4 | 5 | 5 | 1/5 (Δ[Na2SO4])/(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 = -1/3 (Δ[Na2SO3])/(Δt) = -1/2 (Δ[NaIO3])/(Δt) = -1/2 (Δ[NaHSO3])/(Δt) = (Δ[H2O])/(Δt) = (Δ[I2])/(Δt) = 1/5 (Δ[Na2SO4])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| sodium sulfite | sodium iodate | sodium bisulfite | water | iodine | sodium sulfate formula | Na_2SO_3 | NaIO_3 | NaHSO_3 | H_2O | I_2 | Na_2SO_4 Hill formula | Na_2O_3S | INaO_3 | HNaO_3S | H_2O | I_2 | Na_2O_4S name | sodium sulfite | sodium iodate | sodium bisulfite | water | iodine | sodium sulfate IUPAC name | disodium sulfite | sodium iodate | | water | molecular iodine | disodium sulfate