H2O2 + Fe(OH)2 = Fe(OH)3

H_2O_2 (hydrogen peroxide) + Fe(OH)_2 (iron(II) hydroxide) ⟶ Fe(OH)_3 (iron(III) hydroxide)

Balance the chemical equation algebraically: H_2O_2 + Fe(OH)_2 ⟶ Fe(OH)_3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O_2 + c_2 Fe(OH)_2 ⟶ c_3 Fe(OH)_3 Set the number of atoms in the reactants equal to the number of atoms in the products for H, O and Fe: H: | 2 c_1 + 2 c_2 = 3 c_3 O: | 2 c_1 + 2 c_2 = 3 c_3 Fe: | 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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 2 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | H_2O_2 + 2 Fe(OH)_2 ⟶ 2 Fe(OH)_3

+ ⟶

hydrogen peroxide + iron(II) hydroxide ⟶ iron(III) hydroxide

Construct the equilibrium constant, K, expression for: H_2O_2 + Fe(OH)_2 ⟶ Fe(OH)_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: H_2O_2 + 2 Fe(OH)_2 ⟶ 2 Fe(OH)_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 H_2O_2 | 1 | -1 Fe(OH)_2 | 2 | -2 Fe(OH)_3 | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2O_2 | 1 | -1 | ([H2O2])^(-1) Fe(OH)_2 | 2 | -2 | ([Fe(OH)2])^(-2) Fe(OH)_3 | 2 | 2 | ([Fe(OH)3])^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 = ([H2O2])^(-1) ([Fe(OH)2])^(-2) ([Fe(OH)3])^2 = ([Fe(OH)3])^2/([H2O2] ([Fe(OH)2])^2)

Construct the rate of reaction expression for: H_2O_2 + Fe(OH)_2 ⟶ Fe(OH)_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: H_2O_2 + 2 Fe(OH)_2 ⟶ 2 Fe(OH)_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 H_2O_2 | 1 | -1 Fe(OH)_2 | 2 | -2 Fe(OH)_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 H_2O_2 | 1 | -1 | -(Δ[H2O2])/(Δt) Fe(OH)_2 | 2 | -2 | -1/2 (Δ[Fe(OH)2])/(Δt) Fe(OH)_3 | 2 | 2 | 1/2 (Δ[Fe(OH)3])/(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[H2O2])/(Δt) = -1/2 (Δ[Fe(OH)2])/(Δt) = 1/2 (Δ[Fe(OH)3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen peroxide | iron(II) hydroxide | iron(III) hydroxide formula | H_2O_2 | Fe(OH)_2 | Fe(OH)_3 Hill formula | H_2O_2 | FeH_2O_2 | FeH_3O_3 name | hydrogen peroxide | iron(II) hydroxide | iron(III) hydroxide IUPAC name | hydrogen peroxide | ferrous dihydroxide | ferric trihydroxide

| hydrogen peroxide | iron(II) hydroxide | iron(III) hydroxide molar mass | 34.014 g/mol | 89.86 g/mol | 106.87 g/mol phase | liquid (at STP) | | melting point | -0.43 °C | | boiling point | 150.2 °C | | density | 1.44 g/cm^3 | | solubility in water | miscible | | surface tension | 0.0804 N/m | | dynamic viscosity | 0.001249 Pa s (at 20 °C) | |