H2O + KI + NaOCl = KOH + I2 + NaCl

H_2O water + KI potassium iodide + NaOCl sodium hypochlorite ⟶ KOH potassium hydroxide + I_2 iodine + NaCl sodium chloride

Balance the chemical equation algebraically: H_2O + KI + NaOCl ⟶ KOH + I_2 + NaCl Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O + c_2 KI + c_3 NaOCl ⟶ c_4 KOH + c_5 I_2 + c_6 NaCl Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, I, K, Cl and Na: H: | 2 c_1 = c_4 O: | c_1 + c_3 = c_4 I: | c_2 = 2 c_5 K: | c_2 = c_4 Cl: | c_3 = c_6 Na: | c_3 = c_6 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 = 1 c_4 = 2 c_5 = 1 c_6 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | H_2O + 2 KI + NaOCl ⟶ 2 KOH + I_2 + NaCl

+ + ⟶ + +

water + potassium iodide + sodium hypochlorite ⟶ potassium hydroxide + iodine + sodium chloride

Construct the equilibrium constant, K, expression for: H_2O + KI + NaOCl ⟶ KOH + I_2 + NaCl 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: H_2O + 2 KI + NaOCl ⟶ 2 KOH + I_2 + NaCl 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 H_2O | 1 | -1 KI | 2 | -2 NaOCl | 1 | -1 KOH | 2 | 2 I_2 | 1 | 1 NaCl | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2O | 1 | -1 | ([H2O])^(-1) KI | 2 | -2 | ([KI])^(-2) NaOCl | 1 | -1 | ([NaOCl])^(-1) KOH | 2 | 2 | ([KOH])^2 I_2 | 1 | 1 | [I2] NaCl | 1 | 1 | [NaCl] 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 = ([H2O])^(-1) ([KI])^(-2) ([NaOCl])^(-1) ([KOH])^2 [I2] [NaCl] = (([KOH])^2 [I2] [NaCl])/([H2O] ([KI])^2 [NaOCl])

Construct the rate of reaction expression for: H_2O + KI + NaOCl ⟶ KOH + I_2 + NaCl 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: H_2O + 2 KI + NaOCl ⟶ 2 KOH + I_2 + NaCl 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 H_2O | 1 | -1 KI | 2 | -2 NaOCl | 1 | -1 KOH | 2 | 2 I_2 | 1 | 1 NaCl | 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 H_2O | 1 | -1 | -(Δ[H2O])/(Δt) KI | 2 | -2 | -1/2 (Δ[KI])/(Δt) NaOCl | 1 | -1 | -(Δ[NaOCl])/(Δt) KOH | 2 | 2 | 1/2 (Δ[KOH])/(Δt) I_2 | 1 | 1 | (Δ[I2])/(Δt) NaCl | 1 | 1 | (Δ[NaCl])/(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[H2O])/(Δt) = -1/2 (Δ[KI])/(Δt) = -(Δ[NaOCl])/(Δt) = 1/2 (Δ[KOH])/(Δt) = (Δ[I2])/(Δt) = (Δ[NaCl])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| water | potassium iodide | sodium hypochlorite | potassium hydroxide | iodine | sodium chloride formula | H_2O | KI | NaOCl | KOH | I_2 | NaCl Hill formula | H_2O | IK | ClNaO | HKO | I_2 | ClNa name | water | potassium iodide | sodium hypochlorite | potassium hydroxide | iodine | sodium chloride IUPAC name | water | potassium iodide | sodium hypochlorite | potassium hydroxide | molecular iodine | sodium chloride

| water | potassium iodide | sodium hypochlorite | potassium hydroxide | iodine | sodium chloride molar mass | 18.015 g/mol | 166.0028 g/mol | 74.44 g/mol | 56.105 g/mol | 253.80894 g/mol | 58.44 g/mol phase | liquid (at STP) | solid (at STP) | liquid (at STP) | solid (at STP) | solid (at STP) | solid (at STP) melting point | 0 °C | 681 °C | -6 °C | 406 °C | 113 °C | 801 °C boiling point | 99.9839 °C | 1330 °C | | 1327 °C | 184 °C | 1413 °C density | 1 g/cm^3 | 3.123 g/cm^3 | 1.11 g/cm^3 | 2.044 g/cm^3 | 4.94 g/cm^3 | 2.16 g/cm^3 solubility in water | | | miscible | soluble | | soluble surface tension | 0.0728 N/m | | | | | dynamic viscosity | 8.9×10^-4 Pa s (at 25 °C) | 0.0010227 Pa s (at 732.9 °C) | | 0.001 Pa s (at 550 °C) | 0.00227 Pa s (at 116 °C) | odor | odorless | | | | | odorless