Input interpretation
HNO_3 nitric acid + FeI_2 ferrous iodide ⟶ H_2O water + NO_2 nitrogen dioxide + Fe(NO_3)_3 ferric nitrate + HIO_3 iodic acid
Balanced equation
Balance the chemical equation algebraically: HNO_3 + FeI_2 ⟶ H_2O + NO_2 + Fe(NO_3)_3 + HIO_3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HNO_3 + c_2 FeI_2 ⟶ c_3 H_2O + c_4 NO_2 + c_5 Fe(NO_3)_3 + c_6 HIO_3 Set the number of atoms in the reactants equal to the number of atoms in the products for H, N, O, Fe and I: H: | c_1 = 2 c_3 + c_6 N: | c_1 = c_4 + 3 c_5 O: | 3 c_1 = c_3 + 2 c_4 + 9 c_5 + 3 c_6 Fe: | c_2 = c_5 I: | 2 c_2 = c_6 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 = 16 c_2 = 1 c_3 = 7 c_4 = 13 c_5 = 1 c_6 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 16 HNO_3 + FeI_2 ⟶ 7 H_2O + 13 NO_2 + Fe(NO_3)_3 + 2 HIO_3
Structures
+ ⟶ + + +
Names
nitric acid + ferrous iodide ⟶ water + nitrogen dioxide + ferric nitrate + iodic acid
Equilibrium constant
Construct the equilibrium constant, K, expression for: HNO_3 + FeI_2 ⟶ H_2O + NO_2 + Fe(NO_3)_3 + HIO_3 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: 16 HNO_3 + FeI_2 ⟶ 7 H_2O + 13 NO_2 + Fe(NO_3)_3 + 2 HIO_3 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 HNO_3 | 16 | -16 FeI_2 | 1 | -1 H_2O | 7 | 7 NO_2 | 13 | 13 Fe(NO_3)_3 | 1 | 1 HIO_3 | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HNO_3 | 16 | -16 | ([HNO3])^(-16) FeI_2 | 1 | -1 | ([FeI2])^(-1) H_2O | 7 | 7 | ([H2O])^7 NO_2 | 13 | 13 | ([NO2])^13 Fe(NO_3)_3 | 1 | 1 | [Fe(NO3)3] HIO_3 | 2 | 2 | ([HIO3])^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 = ([HNO3])^(-16) ([FeI2])^(-1) ([H2O])^7 ([NO2])^13 [Fe(NO3)3] ([HIO3])^2 = (([H2O])^7 ([NO2])^13 [Fe(NO3)3] ([HIO3])^2)/(([HNO3])^16 [FeI2])
Rate of reaction
Construct the rate of reaction expression for: HNO_3 + FeI_2 ⟶ H_2O + NO_2 + Fe(NO_3)_3 + HIO_3 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: 16 HNO_3 + FeI_2 ⟶ 7 H_2O + 13 NO_2 + Fe(NO_3)_3 + 2 HIO_3 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 HNO_3 | 16 | -16 FeI_2 | 1 | -1 H_2O | 7 | 7 NO_2 | 13 | 13 Fe(NO_3)_3 | 1 | 1 HIO_3 | 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 HNO_3 | 16 | -16 | -1/16 (Δ[HNO3])/(Δt) FeI_2 | 1 | -1 | -(Δ[FeI2])/(Δt) H_2O | 7 | 7 | 1/7 (Δ[H2O])/(Δt) NO_2 | 13 | 13 | 1/13 (Δ[NO2])/(Δt) Fe(NO_3)_3 | 1 | 1 | (Δ[Fe(NO3)3])/(Δt) HIO_3 | 2 | 2 | 1/2 (Δ[HIO3])/(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 = -1/16 (Δ[HNO3])/(Δt) = -(Δ[FeI2])/(Δt) = 1/7 (Δ[H2O])/(Δt) = 1/13 (Δ[NO2])/(Δt) = (Δ[Fe(NO3)3])/(Δt) = 1/2 (Δ[HIO3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)
Chemical names and formulas
| nitric acid | ferrous iodide | water | nitrogen dioxide | ferric nitrate | iodic acid formula | HNO_3 | FeI_2 | H_2O | NO_2 | Fe(NO_3)_3 | HIO_3 Hill formula | HNO_3 | FeI_2 | H_2O | NO_2 | FeN_3O_9 | HIO_3 name | nitric acid | ferrous iodide | water | nitrogen dioxide | ferric nitrate | iodic acid IUPAC name | nitric acid | diiodoiron | water | Nitrogen dioxide | iron(+3) cation trinitrate | iodic acid