Zn + HgCl2 = ZnCl2 + Hg

Zn zinc + HgCl_2 mercuric chloride ⟶ ZnCl_2 zinc chloride + Hg mercury

Balance the chemical equation algebraically: Zn + HgCl_2 ⟶ ZnCl_2 + Hg Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Zn + c_2 HgCl_2 ⟶ c_3 ZnCl_2 + c_4 Hg Set the number of atoms in the reactants equal to the number of atoms in the products for Zn, Cl and Hg: Zn: | c_1 = c_3 Cl: | 2 c_2 = 2 c_3 Hg: | 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 + HgCl_2 ⟶ ZnCl_2 + Hg

+ ⟶ +

zinc + mercuric chloride ⟶ zinc chloride + mercury

| zinc | mercuric chloride | zinc chloride | mercury molecular enthalpy | 0 kJ/mol | -224.3 kJ/mol | -415.1 kJ/mol | 0 kJ/mol total enthalpy | 0 kJ/mol | -224.3 kJ/mol | -415.1 kJ/mol | 0 kJ/mol | H_initial = -224.3 kJ/mol | | H_final = -415.1 kJ/mol | ΔH_rxn^0 | -415.1 kJ/mol - -224.3 kJ/mol = -190.8 kJ/mol (exothermic) | | |

Construct the equilibrium constant, K, expression for: Zn + HgCl_2 ⟶ ZnCl_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: Zn + HgCl_2 ⟶ ZnCl_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 Zn | 1 | -1 HgCl_2 | 1 | -1 ZnCl_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 Zn | 1 | -1 | ([Zn])^(-1) HgCl_2 | 1 | -1 | ([HgCl2])^(-1) ZnCl_2 | 1 | 1 | [ZnCl2] 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 = ([Zn])^(-1) ([HgCl2])^(-1) [ZnCl2] [Hg] = ([ZnCl2] [Hg])/([Zn] [HgCl2])

Construct the rate of reaction expression for: Zn + HgCl_2 ⟶ ZnCl_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: Zn + HgCl_2 ⟶ ZnCl_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 Zn | 1 | -1 HgCl_2 | 1 | -1 ZnCl_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 Zn | 1 | -1 | -(Δ[Zn])/(Δt) HgCl_2 | 1 | -1 | -(Δ[HgCl2])/(Δt) ZnCl_2 | 1 | 1 | (Δ[ZnCl2])/(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[Zn])/(Δt) = -(Δ[HgCl2])/(Δt) = (Δ[ZnCl2])/(Δt) = (Δ[Hg])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| zinc | mercuric chloride | zinc chloride | mercury formula | Zn | HgCl_2 | ZnCl_2 | Hg Hill formula | Zn | Cl_2Hg | Cl_2Zn | Hg name | zinc | mercuric chloride | zinc chloride | mercury IUPAC name | zinc | dichloromercury | zinc dichloride | mercury

| zinc | mercuric chloride | zinc chloride | mercury molar mass | 65.38 g/mol | 271.49 g/mol | 136.3 g/mol | 200.592 g/mol phase | solid (at STP) | solid (at STP) | solid (at STP) | liquid (at STP) melting point | 420 °C | 277 °C | 293 °C | -38.87 °C boiling point | 907 °C | 302 °C | | 356.6 °C density | 7.14 g/cm^3 | 5.44 g/cm^3 | | 13.534 g/cm^3 solubility in water | insoluble | | soluble | slightly soluble surface tension | | | | 0.47 N/m dynamic viscosity | | | | 0.001526 Pa s (at 25 °C) odor | odorless | odorless | odorless | odorless