Fe + H2O2 = Fe(OH)2

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

Balance the chemical equation algebraically: Fe + H_2O_2 ⟶ Fe(OH)_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Fe + c_2 H_2O_2 ⟶ c_3 Fe(OH)_2 Set the number of atoms in the reactants equal to the number of atoms in the products for Fe, H and O: Fe: | c_1 = c_3 H: | 2 c_2 = 2 c_3 O: | 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_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: | | Fe + H_2O_2 ⟶ Fe(OH)_2

+ ⟶

iron + hydrogen peroxide ⟶ iron(II) hydroxide

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

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

| iron | hydrogen peroxide | iron(II) hydroxide formula | Fe | H_2O_2 | Fe(OH)_2 Hill formula | Fe | H_2O_2 | FeH_2O_2 name | iron | hydrogen peroxide | iron(II) hydroxide IUPAC name | iron | hydrogen peroxide | ferrous dihydroxide

| iron | hydrogen peroxide | iron(II) hydroxide molar mass | 55.845 g/mol | 34.014 g/mol | 89.86 g/mol phase | solid (at STP) | liquid (at STP) | melting point | 1535 °C | -0.43 °C | boiling point | 2750 °C | 150.2 °C | density | 7.874 g/cm^3 | 1.44 g/cm^3 | solubility in water | insoluble | miscible | surface tension | | 0.0804 N/m | dynamic viscosity | | 0.001249 Pa s (at 20 °C) |