H2O2 + HgO = H2O + O2 + Hg

H_2O_2 hydrogen peroxide + HgO mercuric oxide ⟶ H_2O water + O_2 oxygen + Hg mercury

Balance the chemical equation algebraically: H_2O_2 + HgO ⟶ H_2O + O_2 + Hg Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O_2 + c_2 HgO ⟶ c_3 H_2O + c_4 O_2 + c_5 Hg Set the number of atoms in the reactants equal to the number of atoms in the products for H, O and Hg: H: | 2 c_1 = 2 c_3 O: | 2 c_1 + c_2 = c_3 + 2 c_4 Hg: | c_2 = c_5 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_3 = 1 c_4 = c_2/2 + 1/2 c_5 = c_2 The resulting system of equations is still underdetermined, so an additional coefficient must be set arbitrarily. Set c_2 = 1 and solve for the remaining coefficients: c_1 = 1 c_2 = 1 c_3 = 1 c_4 = 1 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | H_2O_2 + HgO ⟶ H_2O + O_2 + Hg

+ ⟶ + +

hydrogen peroxide + mercuric oxide ⟶ water + oxygen + mercury

| hydrogen peroxide | mercuric oxide | water | oxygen | mercury molecular free energy | -120.4 kJ/mol | -59 kJ/mol | -237.1 kJ/mol | 231.7 kJ/mol | 0 kJ/mol total free energy | -120.4 kJ/mol | -59 kJ/mol | -237.1 kJ/mol | 231.7 kJ/mol | 0 kJ/mol | G_initial = -179.4 kJ/mol | | G_final = -5.4 kJ/mol | | ΔG_rxn^0 | -5.4 kJ/mol - -179.4 kJ/mol = 174 kJ/mol (endergonic) | | | |

Construct the equilibrium constant, K, expression for: H_2O_2 + HgO ⟶ H_2O + O_2 + Hg 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 + HgO ⟶ H_2O + O_2 + Hg 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 HgO | 1 | -1 H_2O | 1 | 1 O_2 | 1 | 1 Hg | 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 | 1 | -1 | ([H2O2])^(-1) HgO | 1 | -1 | ([HgO])^(-1) H_2O | 1 | 1 | [H2O] O_2 | 1 | 1 | [O2] Hg | 1 | 1 | [Hg] 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) ([HgO])^(-1) [H2O] [O2] [Hg] = ([H2O] [O2] [Hg])/([H2O2] [HgO])

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

| hydrogen peroxide | mercuric oxide | water | oxygen | mercury formula | H_2O_2 | HgO | H_2O | O_2 | Hg name | hydrogen peroxide | mercuric oxide | water | oxygen | mercury IUPAC name | hydrogen peroxide | oxomercury | water | molecular oxygen | mercury

| hydrogen peroxide | mercuric oxide | water | oxygen | mercury molar mass | 34.014 g/mol | 216.591 g/mol | 18.015 g/mol | 31.998 g/mol | 200.592 g/mol phase | liquid (at STP) | solid (at STP) | liquid (at STP) | gas (at STP) | liquid (at STP) melting point | -0.43 °C | 500 °C | 0 °C | -218 °C | -38.87 °C boiling point | 150.2 °C | | 99.9839 °C | -183 °C | 356.6 °C density | 1.44 g/cm^3 | 11.14 g/cm^3 | 1 g/cm^3 | 0.001429 g/cm^3 (at 0 °C) | 13.534 g/cm^3 solubility in water | miscible | insoluble | | | slightly soluble surface tension | 0.0804 N/m | | 0.0728 N/m | 0.01347 N/m | 0.47 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) | 0.001526 Pa s (at 25 °C) odor | | odorless | odorless | odorless | odorless