Al + Fe2O3 = Fe + Al3O3

Al aluminum + Fe_2O_3 iron(III) oxide ⟶ Fe iron + Al3O3

Balance the chemical equation algebraically: Al + Fe_2O_3 ⟶ Fe + Al3O3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Al + c_2 Fe_2O_3 ⟶ c_3 Fe + c_4 Al3O3 Set the number of atoms in the reactants equal to the number of atoms in the products for Al, Fe and O: Al: | c_1 = 3 c_4 Fe: | 2 c_2 = c_3 O: | 3 c_2 = 3 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 3 c_2 = 1 c_3 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 Al + Fe_2O_3 ⟶ 2 Fe + Al3O3

+ ⟶ + Al3O3

aluminum + iron(III) oxide ⟶ iron + Al3O3

Construct the equilibrium constant, K, expression for: Al + Fe_2O_3 ⟶ Fe + Al3O3 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 Al + Fe_2O_3 ⟶ 2 Fe + Al3O3 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 Al | 3 | -3 Fe_2O_3 | 1 | -1 Fe | 2 | 2 Al3O3 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Al | 3 | -3 | ([Al])^(-3) Fe_2O_3 | 1 | -1 | ([Fe2O3])^(-1) Fe | 2 | 2 | ([Fe])^2 Al3O3 | 1 | 1 | [Al3O3] 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 = ([Al])^(-3) ([Fe2O3])^(-1) ([Fe])^2 [Al3O3] = (([Fe])^2 [Al3O3])/(([Al])^3 [Fe2O3])

Construct the rate of reaction expression for: Al + Fe_2O_3 ⟶ Fe + Al3O3 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 Al + Fe_2O_3 ⟶ 2 Fe + Al3O3 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 Al | 3 | -3 Fe_2O_3 | 1 | -1 Fe | 2 | 2 Al3O3 | 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 Al | 3 | -3 | -1/3 (Δ[Al])/(Δt) Fe_2O_3 | 1 | -1 | -(Δ[Fe2O3])/(Δt) Fe | 2 | 2 | 1/2 (Δ[Fe])/(Δt) Al3O3 | 1 | 1 | (Δ[Al3O3])/(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[Al])/(Δt) = -(Δ[Fe2O3])/(Δt) = 1/2 (Δ[Fe])/(Δt) = (Δ[Al3O3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| aluminum | iron(III) oxide | iron | Al3O3 formula | Al | Fe_2O_3 | Fe | Al3O3 name | aluminum | iron(III) oxide | iron |

| aluminum | iron(III) oxide | iron | Al3O3 molar mass | 26.9815385 g/mol | 159.69 g/mol | 55.845 g/mol | 128.94 g/mol phase | solid (at STP) | solid (at STP) | solid (at STP) | melting point | 660.4 °C | 1565 °C | 1535 °C | boiling point | 2460 °C | | 2750 °C | density | 2.7 g/cm^3 | 5.26 g/cm^3 | 7.874 g/cm^3 | solubility in water | insoluble | insoluble | insoluble | surface tension | 0.817 N/m | | | dynamic viscosity | 1.5×10^-4 Pa s (at 760 °C) | | | odor | odorless | odorless | |