HCl + PbO2 = Pb + HClO

HCl hydrogen chloride + PbO_2 lead dioxide ⟶ Pb lead + HOCl hypochlorous acid

Balance the chemical equation algebraically: HCl + PbO_2 ⟶ Pb + HOCl Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HCl + c_2 PbO_2 ⟶ c_3 Pb + c_4 HOCl Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, H, O and Pb: Cl: | c_1 = c_4 H: | c_1 = c_4 O: | 2 c_2 = c_4 Pb: | 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 = 2 c_2 = 1 c_3 = 1 c_4 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 HCl + PbO_2 ⟶ Pb + 2 HOCl

+ ⟶ +

hydrogen chloride + lead dioxide ⟶ lead + hypochlorous acid

Construct the equilibrium constant, K, expression for: HCl + PbO_2 ⟶ Pb + HOCl 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: 2 HCl + PbO_2 ⟶ Pb + 2 HOCl 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 | 2 | -2 PbO_2 | 1 | -1 Pb | 1 | 1 HOCl | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HCl | 2 | -2 | ([HCl])^(-2) PbO_2 | 1 | -1 | ([PbO2])^(-1) Pb | 1 | 1 | [Pb] HOCl | 2 | 2 | ([HOCl])^2 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])^(-2) ([PbO2])^(-1) [Pb] ([HOCl])^2 = ([Pb] ([HOCl])^2)/(([HCl])^2 [PbO2])

Construct the rate of reaction expression for: HCl + PbO_2 ⟶ Pb + HOCl 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: 2 HCl + PbO_2 ⟶ Pb + 2 HOCl 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 | 2 | -2 PbO_2 | 1 | -1 Pb | 1 | 1 HOCl | 2 | 2 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 | 2 | -2 | -1/2 (Δ[HCl])/(Δt) PbO_2 | 1 | -1 | -(Δ[PbO2])/(Δt) Pb | 1 | 1 | (Δ[Pb])/(Δt) HOCl | 2 | 2 | 1/2 (Δ[HOCl])/(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 = -1/2 (Δ[HCl])/(Δt) = -(Δ[PbO2])/(Δt) = (Δ[Pb])/(Δt) = 1/2 (Δ[HOCl])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen chloride | lead dioxide | lead | hypochlorous acid formula | HCl | PbO_2 | Pb | HOCl Hill formula | ClH | O_2Pb | Pb | ClHO name | hydrogen chloride | lead dioxide | lead | hypochlorous acid

| hydrogen chloride | lead dioxide | lead | hypochlorous acid molar mass | 36.46 g/mol | 239.2 g/mol | 207.2 g/mol | 52.46 g/mol phase | gas (at STP) | solid (at STP) | solid (at STP) | melting point | -114.17 °C | 290 °C | 327.4 °C | boiling point | -85 °C | | 1740 °C | density | 0.00149 g/cm^3 (at 25 °C) | 9.58 g/cm^3 | 11.34 g/cm^3 | solubility in water | miscible | insoluble | insoluble | soluble dynamic viscosity | | | 0.00183 Pa s (at 38 °C) |