Zn + MnCl2 = ZnCl2 + Mn

Zn zinc + MnCl_2 manganese(II) chloride ⟶ ZnCl_2 zinc chloride + Mn manganese

Balance the chemical equation algebraically: Zn + MnCl_2 ⟶ ZnCl_2 + Mn Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Zn + c_2 MnCl_2 ⟶ c_3 ZnCl_2 + c_4 Mn Set the number of atoms in the reactants equal to the number of atoms in the products for Zn, Cl and Mn: Zn: | c_1 = c_3 Cl: | 2 c_2 = 2 c_3 Mn: | 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 + MnCl_2 ⟶ ZnCl_2 + Mn

+ ⟶ +

zinc + manganese(II) chloride ⟶ zinc chloride + manganese

| zinc | manganese(II) chloride | zinc chloride | manganese molecular enthalpy | 0 kJ/mol | -481.3 kJ/mol | -415.1 kJ/mol | 0 kJ/mol total enthalpy | 0 kJ/mol | -481.3 kJ/mol | -415.1 kJ/mol | 0 kJ/mol | H_initial = -481.3 kJ/mol | | H_final = -415.1 kJ/mol | ΔH_rxn^0 | -415.1 kJ/mol - -481.3 kJ/mol = 66.2 kJ/mol (endothermic) | | |

Construct the equilibrium constant, K, expression for: Zn + MnCl_2 ⟶ ZnCl_2 + Mn 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 + MnCl_2 ⟶ ZnCl_2 + Mn 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 MnCl_2 | 1 | -1 ZnCl_2 | 1 | 1 Mn | 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) MnCl_2 | 1 | -1 | ([MnCl2])^(-1) ZnCl_2 | 1 | 1 | [ZnCl2] Mn | 1 | 1 | [Mn] 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) ([MnCl2])^(-1) [ZnCl2] [Mn] = ([ZnCl2] [Mn])/([Zn] [MnCl2])

Construct the rate of reaction expression for: Zn + MnCl_2 ⟶ ZnCl_2 + Mn 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 + MnCl_2 ⟶ ZnCl_2 + Mn 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 MnCl_2 | 1 | -1 ZnCl_2 | 1 | 1 Mn | 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) MnCl_2 | 1 | -1 | -(Δ[MnCl2])/(Δt) ZnCl_2 | 1 | 1 | (Δ[ZnCl2])/(Δt) Mn | 1 | 1 | (Δ[Mn])/(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[MnCl2])/(Δt) = (Δ[ZnCl2])/(Δt) = (Δ[Mn])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| zinc | manganese(II) chloride | zinc chloride | manganese formula | Zn | MnCl_2 | ZnCl_2 | Mn Hill formula | Zn | Cl_2Mn | Cl_2Zn | Mn name | zinc | manganese(II) chloride | zinc chloride | manganese IUPAC name | zinc | dichloromanganese | zinc dichloride | manganese

| zinc | manganese(II) chloride | zinc chloride | manganese molar mass | 65.38 g/mol | 125.8 g/mol | 136.3 g/mol | 54.938044 g/mol phase | solid (at STP) | solid (at STP) | solid (at STP) | solid (at STP) melting point | 420 °C | 652 °C | 293 °C | 1244 °C boiling point | 907 °C | | | 1962 °C density | 7.14 g/cm^3 | 2.98 g/cm^3 | | 7.3 g/cm^3 solubility in water | insoluble | | soluble | insoluble odor | odorless | | odorless |