Cl2 + KOH + Cr3I3 = H2O + KCl + K2CrO4 + KIO4

Cl_2 chlorine + KOH potassium hydroxide + Cr3I3 ⟶ H_2O water + KCl potassium chloride + K_2CrO_4 potassium chromate + KIO_4 potassium periodate

Balance the chemical equation algebraically: Cl_2 + KOH + Cr3I3 ⟶ H_2O + KCl + K_2CrO_4 + KIO_4 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Cl_2 + c_2 KOH + c_3 Cr3I3 ⟶ c_4 H_2O + c_5 KCl + c_6 K_2CrO_4 + c_7 KIO_4 Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, H, K, O, Cr and I: Cl: | 2 c_1 = c_5 H: | c_2 = 2 c_4 K: | c_2 = c_5 + 2 c_6 + c_7 O: | c_2 = c_4 + 4 c_6 + 4 c_7 Cr: | 3 c_3 = c_6 I: | 3 c_3 = c_7 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 = 39/2 c_2 = 48 c_3 = 1 c_4 = 24 c_5 = 39 c_6 = 3 c_7 = 3 Multiply by the least common denominator, 2, to eliminate fractional coefficients: c_1 = 39 c_2 = 96 c_3 = 2 c_4 = 48 c_5 = 78 c_6 = 6 c_7 = 6 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 39 Cl_2 + 96 KOH + 2 Cr3I3 ⟶ 48 H_2O + 78 KCl + 6 K_2CrO_4 + 6 KIO_4

+ + Cr3I3 ⟶ + + +

chlorine + potassium hydroxide + Cr3I3 ⟶ water + potassium chloride + potassium chromate + potassium periodate

Construct the equilibrium constant, K, expression for: Cl_2 + KOH + Cr3I3 ⟶ H_2O + KCl + K_2CrO_4 + KIO_4 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: 39 Cl_2 + 96 KOH + 2 Cr3I3 ⟶ 48 H_2O + 78 KCl + 6 K_2CrO_4 + 6 KIO_4 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 Cl_2 | 39 | -39 KOH | 96 | -96 Cr3I3 | 2 | -2 H_2O | 48 | 48 KCl | 78 | 78 K_2CrO_4 | 6 | 6 KIO_4 | 6 | 6 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Cl_2 | 39 | -39 | ([Cl2])^(-39) KOH | 96 | -96 | ([KOH])^(-96) Cr3I3 | 2 | -2 | ([Cr3I3])^(-2) H_2O | 48 | 48 | ([H2O])^48 KCl | 78 | 78 | ([KCl])^78 K_2CrO_4 | 6 | 6 | ([K2CrO4])^6 KIO_4 | 6 | 6 | ([KIO4])^6 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 = ([Cl2])^(-39) ([KOH])^(-96) ([Cr3I3])^(-2) ([H2O])^48 ([KCl])^78 ([K2CrO4])^6 ([KIO4])^6 = (([H2O])^48 ([KCl])^78 ([K2CrO4])^6 ([KIO4])^6)/(([Cl2])^39 ([KOH])^96 ([Cr3I3])^2)

Construct the rate of reaction expression for: Cl_2 + KOH + Cr3I3 ⟶ H_2O + KCl + K_2CrO_4 + KIO_4 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: 39 Cl_2 + 96 KOH + 2 Cr3I3 ⟶ 48 H_2O + 78 KCl + 6 K_2CrO_4 + 6 KIO_4 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 Cl_2 | 39 | -39 KOH | 96 | -96 Cr3I3 | 2 | -2 H_2O | 48 | 48 KCl | 78 | 78 K_2CrO_4 | 6 | 6 KIO_4 | 6 | 6 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 Cl_2 | 39 | -39 | -1/39 (Δ[Cl2])/(Δt) KOH | 96 | -96 | -1/96 (Δ[KOH])/(Δt) Cr3I3 | 2 | -2 | -1/2 (Δ[Cr3I3])/(Δt) H_2O | 48 | 48 | 1/48 (Δ[H2O])/(Δt) KCl | 78 | 78 | 1/78 (Δ[KCl])/(Δt) K_2CrO_4 | 6 | 6 | 1/6 (Δ[K2CrO4])/(Δt) KIO_4 | 6 | 6 | 1/6 (Δ[KIO4])/(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 = -1/39 (Δ[Cl2])/(Δt) = -1/96 (Δ[KOH])/(Δt) = -1/2 (Δ[Cr3I3])/(Δt) = 1/48 (Δ[H2O])/(Δt) = 1/78 (Δ[KCl])/(Δt) = 1/6 (Δ[K2CrO4])/(Δt) = 1/6 (Δ[KIO4])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| chlorine | potassium hydroxide | Cr3I3 | water | potassium chloride | potassium chromate | potassium periodate formula | Cl_2 | KOH | Cr3I3 | H_2O | KCl | K_2CrO_4 | KIO_4 Hill formula | Cl_2 | HKO | Cr3I3 | H_2O | ClK | CrK_2O_4 | IKO_4 name | chlorine | potassium hydroxide | | water | potassium chloride | potassium chromate | potassium periodate IUPAC name | molecular chlorine | potassium hydroxide | | water | potassium chloride | dipotassium dioxido-dioxochromium | potassium periodate

| chlorine | potassium hydroxide | Cr3I3 | water | potassium chloride | potassium chromate | potassium periodate molar mass | 70.9 g/mol | 56.105 g/mol | 536.702 g/mol | 18.015 g/mol | 74.55 g/mol | 194.19 g/mol | 229.999 g/mol phase | gas (at STP) | solid (at STP) | | liquid (at STP) | solid (at STP) | solid (at STP) | solid (at STP) melting point | -101 °C | 406 °C | | 0 °C | 770 °C | 971 °C | 582 °C boiling point | -34 °C | 1327 °C | | 99.9839 °C | 1420 °C | | density | 0.003214 g/cm^3 (at 0 °C) | 2.044 g/cm^3 | | 1 g/cm^3 | 1.98 g/cm^3 | 2.73 g/cm^3 | 3.618 g/cm^3 solubility in water | | soluble | | | soluble | soluble | surface tension | | | | 0.0728 N/m | | | dynamic viscosity | | 0.001 Pa s (at 550 °C) | | 8.9×10^-4 Pa s (at 25 °C) | | | odor | | | | odorless | odorless | odorless |