HCl + NaClO2 = H2O + Cl2 + NaCl

HCl hydrogen chloride + NaClO_2 sodium chlorite ⟶ H_2O water + Cl_2 chlorine + NaCl sodium chloride

Balance the chemical equation algebraically: HCl + NaClO_2 ⟶ H_2O + Cl_2 + NaCl Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HCl + c_2 NaClO_2 ⟶ c_3 H_2O + c_4 Cl_2 + c_5 NaCl Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, H, Na and O: Cl: | c_1 + c_2 = 2 c_4 + c_5 H: | c_1 = 2 c_3 Na: | c_2 = c_5 O: | 2 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 4 c_2 = 1 c_3 = 2 c_4 = 2 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 4 HCl + NaClO_2 ⟶ 2 H_2O + 2 Cl_2 + NaCl

+ ⟶ + +

hydrogen chloride + sodium chlorite ⟶ water + chlorine + sodium chloride

Construct the equilibrium constant, K, expression for: HCl + NaClO_2 ⟶ H_2O + Cl_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: 4 HCl + NaClO_2 ⟶ 2 H_2O + 2 Cl_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 HCl | 4 | -4 NaClO_2 | 1 | -1 H_2O | 2 | 2 Cl_2 | 2 | 2 NaCl | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HCl | 4 | -4 | ([HCl])^(-4) NaClO_2 | 1 | -1 | ([NaClO2])^(-1) H_2O | 2 | 2 | ([H2O])^2 Cl_2 | 2 | 2 | ([Cl2])^2 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 = ([HCl])^(-4) ([NaClO2])^(-1) ([H2O])^2 ([Cl2])^2 [NaCl] = (([H2O])^2 ([Cl2])^2 [NaCl])/(([HCl])^4 [NaClO2])

Construct the rate of reaction expression for: HCl + NaClO_2 ⟶ H_2O + Cl_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: 4 HCl + NaClO_2 ⟶ 2 H_2O + 2 Cl_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 HCl | 4 | -4 NaClO_2 | 1 | -1 H_2O | 2 | 2 Cl_2 | 2 | 2 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 HCl | 4 | -4 | -1/4 (Δ[HCl])/(Δt) NaClO_2 | 1 | -1 | -(Δ[NaClO2])/(Δt) H_2O | 2 | 2 | 1/2 (Δ[H2O])/(Δt) Cl_2 | 2 | 2 | 1/2 (Δ[Cl2])/(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 = -1/4 (Δ[HCl])/(Δt) = -(Δ[NaClO2])/(Δt) = 1/2 (Δ[H2O])/(Δt) = 1/2 (Δ[Cl2])/(Δt) = (Δ[NaCl])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen chloride | sodium chlorite | water | chlorine | sodium chloride formula | HCl | NaClO_2 | H_2O | Cl_2 | NaCl Hill formula | ClH | ClNaO_2 | H_2O | Cl_2 | ClNa name | hydrogen chloride | sodium chlorite | water | chlorine | sodium chloride IUPAC name | hydrogen chloride | | water | molecular chlorine | sodium chloride