NaCl + KI = KCl + NaI

NaCl sodium chloride + KI potassium iodide ⟶ KCl potassium chloride + NaI sodium iodide

Balance the chemical equation algebraically: NaCl + KI ⟶ KCl + NaI Add stoichiometric coefficients, c_i, to the reactants and products: c_1 NaCl + c_2 KI ⟶ c_3 KCl + c_4 NaI Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, Na, I and K: Cl: | c_1 = c_3 Na: | c_1 = c_4 I: | c_2 = c_4 K: | 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 = 1 c_3 = 1 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | NaCl + KI ⟶ KCl + NaI

+ ⟶ +

sodium chloride + potassium iodide ⟶ potassium chloride + sodium iodide

| sodium chloride | potassium iodide | potassium chloride | sodium iodide molecular enthalpy | -411.2 kJ/mol | -327.9 kJ/mol | -436.5 kJ/mol | -287.8 kJ/mol total enthalpy | -411.2 kJ/mol | -327.9 kJ/mol | -436.5 kJ/mol | -287.8 kJ/mol | H_initial = -739.1 kJ/mol | | H_final = -724.3 kJ/mol | ΔH_rxn^0 | -724.3 kJ/mol - -739.1 kJ/mol = 14.8 kJ/mol (endothermic) | | |

| sodium chloride | potassium iodide | potassium chloride | sodium iodide molecular free energy | -384.1 kJ/mol | -324.9 kJ/mol | -408.5 kJ/mol | -286.1 kJ/mol total free energy | -384.1 kJ/mol | -324.9 kJ/mol | -408.5 kJ/mol | -286.1 kJ/mol | G_initial = -709 kJ/mol | | G_final = -694.6 kJ/mol | ΔG_rxn^0 | -694.6 kJ/mol - -709 kJ/mol = 14.4 kJ/mol (endergonic) | | |

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

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

| sodium chloride | potassium iodide | potassium chloride | sodium iodide formula | NaCl | KI | KCl | NaI Hill formula | ClNa | IK | ClK | INa name | sodium chloride | potassium iodide | potassium chloride | sodium iodide

| sodium chloride | potassium iodide | potassium chloride | sodium iodide molar mass | 58.44 g/mol | 166.0028 g/mol | 74.55 g/mol | 149.89424 g/mol phase | solid (at STP) | solid (at STP) | solid (at STP) | solid (at STP) melting point | 801 °C | 681 °C | 770 °C | 661 °C boiling point | 1413 °C | 1330 °C | 1420 °C | 1300 °C density | 2.16 g/cm^3 | 3.123 g/cm^3 | 1.98 g/cm^3 | 3.67 g/cm^3 solubility in water | soluble | | soluble | dynamic viscosity | | 0.0010227 Pa s (at 732.9 °C) | | 0.0010446 Pa s (at 691 °C) odor | odorless | | odorless |