Zn + CuCl = Cu + ZnCl2

Zn zinc + CuCl cuprous chloride ⟶ Cu copper + ZnCl_2 zinc chloride

Balance the chemical equation algebraically: Zn + CuCl ⟶ Cu + ZnCl_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Zn + c_2 CuCl ⟶ c_3 Cu + c_4 ZnCl_2 Set the number of atoms in the reactants equal to the number of atoms in the products for Zn, Cl and Cu: Zn: | c_1 = c_4 Cl: | c_2 = 2 c_4 Cu: | c_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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 2 c_3 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | Zn + 2 CuCl ⟶ 2 Cu + ZnCl_2

+ ⟶ +

zinc + cuprous chloride ⟶ copper + zinc chloride

| zinc | cuprous chloride | copper | zinc chloride molecular enthalpy | 0 kJ/mol | -137.2 kJ/mol | 0 kJ/mol | -415.1 kJ/mol total enthalpy | 0 kJ/mol | -274.4 kJ/mol | 0 kJ/mol | -415.1 kJ/mol | H_initial = -274.4 kJ/mol | | H_final = -415.1 kJ/mol | ΔH_rxn^0 | -415.1 kJ/mol - -274.4 kJ/mol = -140.7 kJ/mol (exothermic) | | |

Construct the equilibrium constant, K, expression for: Zn + CuCl ⟶ Cu + ZnCl_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: Zn + 2 CuCl ⟶ 2 Cu + ZnCl_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 Zn | 1 | -1 CuCl | 2 | -2 Cu | 2 | 2 ZnCl_2 | 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) CuCl | 2 | -2 | ([CuCl])^(-2) Cu | 2 | 2 | ([Cu])^2 ZnCl_2 | 1 | 1 | [ZnCl2] 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) ([CuCl])^(-2) ([Cu])^2 [ZnCl2] = (([Cu])^2 [ZnCl2])/([Zn] ([CuCl])^2)

Construct the rate of reaction expression for: Zn + CuCl ⟶ Cu + ZnCl_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: Zn + 2 CuCl ⟶ 2 Cu + ZnCl_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 Zn | 1 | -1 CuCl | 2 | -2 Cu | 2 | 2 ZnCl_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 Zn | 1 | -1 | -(Δ[Zn])/(Δt) CuCl | 2 | -2 | -1/2 (Δ[CuCl])/(Δt) Cu | 2 | 2 | 1/2 (Δ[Cu])/(Δt) ZnCl_2 | 1 | 1 | (Δ[ZnCl2])/(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) = -1/2 (Δ[CuCl])/(Δt) = 1/2 (Δ[Cu])/(Δt) = (Δ[ZnCl2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| zinc | cuprous chloride | copper | zinc chloride formula | Zn | CuCl | Cu | ZnCl_2 Hill formula | Zn | ClCu | Cu | Cl_2Zn name | zinc | cuprous chloride | copper | zinc chloride IUPAC name | zinc | | copper | zinc dichloride

| zinc | cuprous chloride | copper | zinc chloride molar mass | 65.38 g/mol | 99 g/mol | 63.546 g/mol | 136.3 g/mol phase | solid (at STP) | solid (at STP) | solid (at STP) | solid (at STP) melting point | 420 °C | 430 °C | 1083 °C | 293 °C boiling point | 907 °C | 1490 °C | 2567 °C | density | 7.14 g/cm^3 | 4.145 g/cm^3 | 8.96 g/cm^3 | solubility in water | insoluble | | insoluble | soluble odor | odorless | | odorless | odorless