HgO = O2 + Hg

HgO (mercuric oxide) ⟶ O_2 (oxygen) + Hg (mercury)

Balance the chemical equation algebraically: HgO ⟶ O_2 + Hg Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HgO ⟶ c_2 O_2 + c_3 Hg Set the number of atoms in the reactants equal to the number of atoms in the products for Hg and O: Hg: | c_1 = c_3 O: | c_1 = 2 c_2 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 = 2 c_2 = 1 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 HgO ⟶ O_2 + 2 Hg

⟶ +

mercuric oxide ⟶ oxygen + mercury

| mercuric oxide | oxygen | mercury molecular enthalpy | -90 kJ/mol | 0 kJ/mol | 0 kJ/mol total enthalpy | -180 kJ/mol | 0 kJ/mol | 0 kJ/mol | H_initial = -180 kJ/mol | H_final = 0 kJ/mol | ΔH_rxn^0 | 0 kJ/mol - -180 kJ/mol = 180 kJ/mol (endothermic) | |

| mercuric oxide | oxygen | mercury molecular free energy | -59 kJ/mol | 231.7 kJ/mol | 0 kJ/mol total free energy | -118 kJ/mol | 231.7 kJ/mol | 0 kJ/mol | G_initial = -118 kJ/mol | G_final = 231.7 kJ/mol | ΔG_rxn^0 | 231.7 kJ/mol - -118 kJ/mol = 349.7 kJ/mol (endergonic) | |

| mercuric oxide | oxygen | mercury molecular entropy | 70 J/(mol K) | 205 J/(mol K) | 76 J/(mol K) total entropy | 140 J/(mol K) | 205 J/(mol K) | 152 J/(mol K) | S_initial = 140 J/(mol K) | S_final = 357 J/(mol K) | ΔS_rxn^0 | 357 J/(mol K) - 140 J/(mol K) = 217 J/(mol K) (endoentropic) | |

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

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

| mercuric oxide | oxygen | mercury formula | HgO | O_2 | Hg name | mercuric oxide | oxygen | mercury IUPAC name | oxomercury | molecular oxygen | mercury

| mercuric oxide | oxygen | mercury molar mass | 216.591 g/mol | 31.998 g/mol | 200.592 g/mol phase | solid (at STP) | gas (at STP) | liquid (at STP) melting point | 500 °C | -218 °C | -38.87 °C boiling point | | -183 °C | 356.6 °C density | 11.14 g/cm^3 | 0.001429 g/cm^3 (at 0 °C) | 13.534 g/cm^3 solubility in water | insoluble | | slightly soluble surface tension | | 0.01347 N/m | 0.47 N/m dynamic viscosity | | 2.055×10^-5 Pa s (at 25 °C) | 0.001526 Pa s (at 25 °C) odor | odorless | odorless | odorless