Al + H2O2 = Al(OH)3

Al aluminum + H_2O_2 hydrogen peroxide ⟶ Al(OH)_3 aluminum hydroxide

Balance the chemical equation algebraically: Al + H_2O_2 ⟶ Al(OH)_3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Al + c_2 H_2O_2 ⟶ c_3 Al(OH)_3 Set the number of atoms in the reactants equal to the number of atoms in the products for Al, H and O: Al: | c_1 = c_3 H: | 2 c_2 = 3 c_3 O: | 2 c_2 = 3 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 = 3/2 c_3 = 1 Multiply by the least common denominator, 2, to eliminate fractional coefficients: c_1 = 2 c_2 = 3 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 Al + 3 H_2O_2 ⟶ 2 Al(OH)_3

+ ⟶

aluminum + hydrogen peroxide ⟶ aluminum hydroxide

Construct the equilibrium constant, K, expression for: Al + H_2O_2 ⟶ Al(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: 2 Al + 3 H_2O_2 ⟶ 2 Al(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 Al | 2 | -2 H_2O_2 | 3 | -3 Al(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 Al | 2 | -2 | ([Al])^(-2) H_2O_2 | 3 | -3 | ([H2O2])^(-3) Al(OH)_3 | 2 | 2 | ([Al(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 = ([Al])^(-2) ([H2O2])^(-3) ([Al(OH)3])^2 = ([Al(OH)3])^2/(([Al])^2 ([H2O2])^3)

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

| aluminum | hydrogen peroxide | aluminum hydroxide formula | Al | H_2O_2 | Al(OH)_3 Hill formula | Al | H_2O_2 | AlH_3O_3 name | aluminum | hydrogen peroxide | aluminum hydroxide

| aluminum | hydrogen peroxide | aluminum hydroxide molar mass | 26.9815385 g/mol | 34.014 g/mol | 78.003 g/mol phase | solid (at STP) | liquid (at STP) | melting point | 660.4 °C | -0.43 °C | boiling point | 2460 °C | 150.2 °C | density | 2.7 g/cm^3 | 1.44 g/cm^3 | solubility in water | insoluble | miscible | surface tension | 0.817 N/m | 0.0804 N/m | dynamic viscosity | 1.5×10^-4 Pa s (at 760 °C) | 0.001249 Pa s (at 20 °C) | odor | odorless | |