Cl2 + K = KCl2

Cl_2 chlorine + K potassium ⟶ KCl2

Balance the chemical equation algebraically: Cl_2 + K ⟶ KCl2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Cl_2 + c_2 K ⟶ c_3 KCl2 Set the number of atoms in the reactants equal to the number of atoms in the products for Cl and K: Cl: | 2 c_1 = 2 c_3 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 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | Cl_2 + K ⟶ KCl2

+ ⟶ KCl2

chlorine + potassium ⟶ KCl2

Construct the equilibrium constant, K, expression for: Cl_2 + K ⟶ KCl2 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: Cl_2 + K ⟶ KCl2 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 | 1 | -1 K | 1 | -1 KCl2 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Cl_2 | 1 | -1 | ([Cl2])^(-1) K | 1 | -1 | ([K])^(-1) KCl2 | 1 | 1 | [KCl2] 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])^(-1) ([K])^(-1) [KCl2] = ([KCl2])/([Cl2] [K])

Construct the rate of reaction expression for: Cl_2 + K ⟶ KCl2 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: Cl_2 + K ⟶ KCl2 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 | 1 | -1 K | 1 | -1 KCl2 | 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 Cl_2 | 1 | -1 | -(Δ[Cl2])/(Δt) K | 1 | -1 | -(Δ[K])/(Δt) KCl2 | 1 | 1 | (Δ[KCl2])/(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[Cl2])/(Δt) = -(Δ[K])/(Δt) = (Δ[KCl2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| chlorine | potassium | KCl2 formula | Cl_2 | K | KCl2 Hill formula | Cl_2 | K | Cl2K name | chlorine | potassium | IUPAC name | molecular chlorine | potassium |

| chlorine | potassium | KCl2 molar mass | 70.9 g/mol | 39.0983 g/mol | 110 g/mol phase | gas (at STP) | solid (at STP) | melting point | -101 °C | 64 °C | boiling point | -34 °C | 760 °C | density | 0.003214 g/cm^3 (at 0 °C) | 0.86 g/cm^3 | solubility in water | | reacts |