KI + CuCl2 = I2 + KCl + CuCl

KI potassium iodide + CuCl_2 copper(II) chloride ⟶ I_2 iodine + KCl potassium chloride + CuCl cuprous chloride

Balance the chemical equation algebraically: KI + CuCl_2 ⟶ I_2 + KCl + CuCl Add stoichiometric coefficients, c_i, to the reactants and products: c_1 KI + c_2 CuCl_2 ⟶ c_3 I_2 + c_4 KCl + c_5 CuCl Set the number of atoms in the reactants equal to the number of atoms in the products for I, K, Cl and Cu: I: | c_1 = 2 c_3 K: | c_1 = c_4 Cl: | 2 c_2 = c_4 + c_5 Cu: | c_2 = c_5 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_3 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 2 c_3 = 1 c_4 = 2 c_5 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 KI + 2 CuCl_2 ⟶ I_2 + 2 KCl + 2 CuCl

+ ⟶ + +

potassium iodide + copper(II) chloride ⟶ iodine + potassium chloride + cuprous chloride

| potassium iodide | copper(II) chloride | iodine | potassium chloride | cuprous chloride molecular enthalpy | -327.9 kJ/mol | -220.1 kJ/mol | 0 kJ/mol | -436.5 kJ/mol | -137.2 kJ/mol total enthalpy | -655.8 kJ/mol | -440.2 kJ/mol | 0 kJ/mol | -873 kJ/mol | -274.4 kJ/mol | H_initial = -1096 kJ/mol | | H_final = -1147 kJ/mol | | ΔH_rxn^0 | -1147 kJ/mol - -1096 kJ/mol = -51.4 kJ/mol (exothermic) | | | |

| potassium iodide | copper(II) chloride | iodine | potassium chloride | cuprous chloride molecular free energy | -324.9 kJ/mol | -175.7 kJ/mol | 0 kJ/mol | -408.5 kJ/mol | -119.9 kJ/mol total free energy | -649.8 kJ/mol | -351.4 kJ/mol | 0 kJ/mol | -817 kJ/mol | -239.8 kJ/mol | G_initial = -1001 kJ/mol | | G_final = -1057 kJ/mol | | ΔG_rxn^0 | -1057 kJ/mol - -1001 kJ/mol = -55.6 kJ/mol (exergonic) | | | |

Construct the equilibrium constant, K, expression for: KI + CuCl_2 ⟶ I_2 + KCl + CuCl 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 KI + 2 CuCl_2 ⟶ I_2 + 2 KCl + 2 CuCl 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 KI | 2 | -2 CuCl_2 | 2 | -2 I_2 | 1 | 1 KCl | 2 | 2 CuCl | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression KI | 2 | -2 | ([KI])^(-2) CuCl_2 | 2 | -2 | ([CuCl2])^(-2) I_2 | 1 | 1 | [I2] KCl | 2 | 2 | ([KCl])^2 CuCl | 2 | 2 | ([CuCl])^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 = ([KI])^(-2) ([CuCl2])^(-2) [I2] ([KCl])^2 ([CuCl])^2 = ([I2] ([KCl])^2 ([CuCl])^2)/(([KI])^2 ([CuCl2])^2)

Construct the rate of reaction expression for: KI + CuCl_2 ⟶ I_2 + KCl + CuCl 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 KI + 2 CuCl_2 ⟶ I_2 + 2 KCl + 2 CuCl 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 KI | 2 | -2 CuCl_2 | 2 | -2 I_2 | 1 | 1 KCl | 2 | 2 CuCl | 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 KI | 2 | -2 | -1/2 (Δ[KI])/(Δt) CuCl_2 | 2 | -2 | -1/2 (Δ[CuCl2])/(Δt) I_2 | 1 | 1 | (Δ[I2])/(Δt) KCl | 2 | 2 | 1/2 (Δ[KCl])/(Δt) CuCl | 2 | 2 | 1/2 (Δ[CuCl])/(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[KI])/(Δt) = -1/2 (Δ[CuCl2])/(Δt) = (Δ[I2])/(Δt) = 1/2 (Δ[KCl])/(Δt) = 1/2 (Δ[CuCl])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| potassium iodide | copper(II) chloride | iodine | potassium chloride | cuprous chloride formula | KI | CuCl_2 | I_2 | KCl | CuCl Hill formula | IK | Cl_2Cu | I_2 | ClK | ClCu name | potassium iodide | copper(II) chloride | iodine | potassium chloride | cuprous chloride IUPAC name | potassium iodide | dichlorocopper | molecular iodine | potassium chloride |

| potassium iodide | copper(II) chloride | iodine | potassium chloride | cuprous chloride molar mass | 166.0028 g/mol | 134.4 g/mol | 253.80894 g/mol | 74.55 g/mol | 99 g/mol phase | solid (at STP) | solid (at STP) | solid (at STP) | solid (at STP) | solid (at STP) melting point | 681 °C | 620 °C | 113 °C | 770 °C | 430 °C boiling point | 1330 °C | | 184 °C | 1420 °C | 1490 °C density | 3.123 g/cm^3 | 3.386 g/cm^3 | 4.94 g/cm^3 | 1.98 g/cm^3 | 4.145 g/cm^3 solubility in water | | | | soluble | dynamic viscosity | 0.0010227 Pa s (at 732.9 °C) | | 0.00227 Pa s (at 116 °C) | | odor | | | | odorless |