KI + Cu(NO3)2 = KNO3 + CuI2

KI potassium iodide + Cu(NO_3)_2 copper(II) nitrate ⟶ KNO_3 potassium nitrate + CuI2

Balance the chemical equation algebraically: KI + Cu(NO_3)_2 ⟶ KNO_3 + CuI2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 KI + c_2 Cu(NO_3)_2 ⟶ c_3 KNO_3 + c_4 CuI2 Set the number of atoms in the reactants equal to the number of atoms in the products for I, K, Cu, N and O: I: | c_1 = 2 c_4 K: | c_1 = c_3 Cu: | c_2 = c_4 N: | 2 c_2 = c_3 O: | 6 c_2 = 3 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 1 c_3 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 KI + Cu(NO_3)_2 ⟶ 2 KNO_3 + CuI2

+ ⟶ + CuI2

potassium iodide + copper(II) nitrate ⟶ potassium nitrate + CuI2

Construct the equilibrium constant, K, expression for: KI + Cu(NO_3)_2 ⟶ KNO_3 + CuI2 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 + Cu(NO_3)_2 ⟶ 2 KNO_3 + CuI2 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 Cu(NO_3)_2 | 1 | -1 KNO_3 | 2 | 2 CuI2 | 1 | 1 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) Cu(NO_3)_2 | 1 | -1 | ([Cu(NO3)2])^(-1) KNO_3 | 2 | 2 | ([KNO3])^2 CuI2 | 1 | 1 | [CuI2] 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) ([Cu(NO3)2])^(-1) ([KNO3])^2 [CuI2] = (([KNO3])^2 [CuI2])/(([KI])^2 [Cu(NO3)2])

Construct the rate of reaction expression for: KI + Cu(NO_3)_2 ⟶ KNO_3 + CuI2 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 + Cu(NO_3)_2 ⟶ 2 KNO_3 + CuI2 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 Cu(NO_3)_2 | 1 | -1 KNO_3 | 2 | 2 CuI2 | 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 KI | 2 | -2 | -1/2 (Δ[KI])/(Δt) Cu(NO_3)_2 | 1 | -1 | -(Δ[Cu(NO3)2])/(Δt) KNO_3 | 2 | 2 | 1/2 (Δ[KNO3])/(Δt) CuI2 | 1 | 1 | (Δ[CuI2])/(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) = -(Δ[Cu(NO3)2])/(Δt) = 1/2 (Δ[KNO3])/(Δt) = (Δ[CuI2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| potassium iodide | copper(II) nitrate | potassium nitrate | CuI2 formula | KI | Cu(NO_3)_2 | KNO_3 | CuI2 Hill formula | IK | CuN_2O_6 | KNO_3 | CuI2 name | potassium iodide | copper(II) nitrate | potassium nitrate |

| potassium iodide | copper(II) nitrate | potassium nitrate | CuI2 molar mass | 166.0028 g/mol | 187.55 g/mol | 101.1 g/mol | 317.355 g/mol phase | solid (at STP) | | solid (at STP) | melting point | 681 °C | | 334 °C | boiling point | 1330 °C | | | density | 3.123 g/cm^3 | | | solubility in water | | | soluble | dynamic viscosity | 0.0010227 Pa s (at 732.9 °C) | | | odor | | | odorless |