Zn + HgO = Hg + ZnO

Zn zinc + HgO mercuric oxide ⟶ Hg mercury + ZnO zinc oxide

Balance the chemical equation algebraically: Zn + HgO ⟶ Hg + ZnO Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Zn + c_2 HgO ⟶ c_3 Hg + c_4 ZnO Set the number of atoms in the reactants equal to the number of atoms in the products for Zn, Hg and O: Zn: | c_1 = c_4 Hg: | c_2 = c_3 O: | c_2 = 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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 1 c_3 = 1 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | Zn + HgO ⟶ Hg + ZnO

+ ⟶ +

zinc + mercuric oxide ⟶ mercury + zinc oxide

| zinc | mercuric oxide | mercury | zinc oxide molecular enthalpy | 0 kJ/mol | -90 kJ/mol | 0 kJ/mol | -350.5 kJ/mol total enthalpy | 0 kJ/mol | -90 kJ/mol | 0 kJ/mol | -350.5 kJ/mol | H_initial = -90 kJ/mol | | H_final = -350.5 kJ/mol | ΔH_rxn^0 | -350.5 kJ/mol - -90 kJ/mol = -260.5 kJ/mol (exothermic) | | |

| zinc | mercuric oxide | mercury | zinc oxide molecular entropy | 42 J/(mol K) | 70 J/(mol K) | 76 J/(mol K) | 44 J/(mol K) total entropy | 42 J/(mol K) | 70 J/(mol K) | 76 J/(mol K) | 44 J/(mol K) | S_initial = 112 J/(mol K) | | S_final = 120 J/(mol K) | ΔS_rxn^0 | 120 J/(mol K) - 112 J/(mol K) = 8 J/(mol K) (endoentropic) | | |

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

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

| zinc | mercuric oxide | mercury | zinc oxide formula | Zn | HgO | Hg | ZnO Hill formula | Zn | HgO | Hg | OZn name | zinc | mercuric oxide | mercury | zinc oxide IUPAC name | zinc | oxomercury | mercury | oxozinc

| zinc | mercuric oxide | mercury | zinc oxide molar mass | 65.38 g/mol | 216.591 g/mol | 200.592 g/mol | 81.38 g/mol phase | solid (at STP) | solid (at STP) | liquid (at STP) | solid (at STP) melting point | 420 °C | 500 °C | -38.87 °C | 1975 °C boiling point | 907 °C | | 356.6 °C | 2360 °C density | 7.14 g/cm^3 | 11.14 g/cm^3 | 13.534 g/cm^3 | 5.6 g/cm^3 solubility in water | insoluble | insoluble | slightly soluble | surface tension | | | 0.47 N/m | dynamic viscosity | | | 0.001526 Pa s (at 25 °C) | odor | odorless | odorless | odorless | odorless