H2O2 = H2O + O2

H_2O_2 (hydrogen peroxide) ⟶ H_2O (water) + O_2 (oxygen)

Balance the chemical equation algebraically: H_2O_2 ⟶ H_2O + O_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O_2 ⟶ c_2 H_2O + c_3 O_2 Set the number of atoms in the reactants equal to the number of atoms in the products for H and O: H: | 2 c_1 = 2 c_2 O: | 2 c_1 = 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_3 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 2 c_3 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 H_2O_2 ⟶ 2 H_2O + O_2

⟶ +

hydrogen peroxide ⟶ water + oxygen

| hydrogen peroxide | water | oxygen molecular free energy | -120.4 kJ/mol | -237.1 kJ/mol | 231.7 kJ/mol total free energy | -240.8 kJ/mol | -474.2 kJ/mol | 231.7 kJ/mol | G_initial = -240.8 kJ/mol | G_final = -242.5 kJ/mol | ΔG_rxn^0 | -242.5 kJ/mol - -240.8 kJ/mol = -1.7 kJ/mol (exergonic) | |

Construct the equilibrium constant, K, expression for: H_2O_2 ⟶ H_2O + O_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: 2 H_2O_2 ⟶ 2 H_2O + O_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 H_2O_2 | 2 | -2 H_2O | 2 | 2 O_2 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2O_2 | 2 | -2 | ([H2O2])^(-2) H_2O | 2 | 2 | ([H2O])^2 O_2 | 1 | 1 | [O2] 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])^(-2) ([H2O])^2 [O2] = (([H2O])^2 [O2])/([H2O2])^2

Construct the rate of reaction expression for: H_2O_2 ⟶ H_2O + O_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: 2 H_2O_2 ⟶ 2 H_2O + O_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 H_2O_2 | 2 | -2 H_2O | 2 | 2 O_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 H_2O_2 | 2 | -2 | -1/2 (Δ[H2O2])/(Δt) H_2O | 2 | 2 | 1/2 (Δ[H2O])/(Δt) O_2 | 1 | 1 | (Δ[O2])/(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[H2O2])/(Δt) = 1/2 (Δ[H2O])/(Δt) = (Δ[O2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen peroxide | water | oxygen formula | H_2O_2 | H_2O | O_2 name | hydrogen peroxide | water | oxygen IUPAC name | hydrogen peroxide | water | molecular oxygen

| hydrogen peroxide | water | oxygen molar mass | 34.014 g/mol | 18.015 g/mol | 31.998 g/mol phase | liquid (at STP) | liquid (at STP) | gas (at STP) melting point | -0.43 °C | 0 °C | -218 °C boiling point | 150.2 °C | 99.9839 °C | -183 °C density | 1.44 g/cm^3 | 1 g/cm^3 | 0.001429 g/cm^3 (at 0 °C) solubility in water | miscible | | surface tension | 0.0804 N/m | 0.0728 N/m | 0.01347 N/m dynamic viscosity | 0.001249 Pa s (at 20 °C) | 8.9×10^-4 Pa s (at 25 °C) | 2.055×10^-5 Pa s (at 25 °C) odor | | odorless | odorless