HCl + KMnO4 + AsH3 = H2O + KCl + MnCl2 + H3AsO4

HCl hydrogen chloride + KMnO_4 potassium permanganate + AsH_3 arsine ⟶ H_2O water + KCl potassium chloride + MnCl_2 manganese(II) chloride + H_3AsO_4 arsenic acid, solid

Balance the chemical equation algebraically: HCl + KMnO_4 + AsH_3 ⟶ H_2O + KCl + MnCl_2 + H_3AsO_4 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HCl + c_2 KMnO_4 + c_3 AsH_3 ⟶ c_4 H_2O + c_5 KCl + c_6 MnCl_2 + c_7 H_3AsO_4 Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, H, K, Mn, O and As: Cl: | c_1 = c_5 + 2 c_6 H: | c_1 + 3 c_3 = 2 c_4 + 3 c_7 K: | c_2 = c_5 Mn: | c_2 = c_6 O: | 4 c_2 = c_4 + 4 c_7 As: | 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 = 24/5 c_2 = 8/5 c_3 = 1 c_4 = 12/5 c_5 = 8/5 c_6 = 8/5 c_7 = 1 Multiply by the least common denominator, 5, to eliminate fractional coefficients: c_1 = 24 c_2 = 8 c_3 = 5 c_4 = 12 c_5 = 8 c_6 = 8 c_7 = 5 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 24 HCl + 8 KMnO_4 + 5 AsH_3 ⟶ 12 H_2O + 8 KCl + 8 MnCl_2 + 5 H_3AsO_4

+ + ⟶ + + +

hydrogen chloride + potassium permanganate + arsine ⟶ water + potassium chloride + manganese(II) chloride + arsenic acid, solid

Construct the equilibrium constant, K, expression for: HCl + KMnO_4 + AsH_3 ⟶ H_2O + KCl + MnCl_2 + H_3AsO_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: 24 HCl + 8 KMnO_4 + 5 AsH_3 ⟶ 12 H_2O + 8 KCl + 8 MnCl_2 + 5 H_3AsO_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 HCl | 24 | -24 KMnO_4 | 8 | -8 AsH_3 | 5 | -5 H_2O | 12 | 12 KCl | 8 | 8 MnCl_2 | 8 | 8 H_3AsO_4 | 5 | 5 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HCl | 24 | -24 | ([HCl])^(-24) KMnO_4 | 8 | -8 | ([KMnO4])^(-8) AsH_3 | 5 | -5 | ([AsH3])^(-5) H_2O | 12 | 12 | ([H2O])^12 KCl | 8 | 8 | ([KCl])^8 MnCl_2 | 8 | 8 | ([MnCl2])^8 H_3AsO_4 | 5 | 5 | ([H3AsO4])^5 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])^(-24) ([KMnO4])^(-8) ([AsH3])^(-5) ([H2O])^12 ([KCl])^8 ([MnCl2])^8 ([H3AsO4])^5 = (([H2O])^12 ([KCl])^8 ([MnCl2])^8 ([H3AsO4])^5)/(([HCl])^24 ([KMnO4])^8 ([AsH3])^5)

Construct the rate of reaction expression for: HCl + KMnO_4 + AsH_3 ⟶ H_2O + KCl + MnCl_2 + H_3AsO_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: 24 HCl + 8 KMnO_4 + 5 AsH_3 ⟶ 12 H_2O + 8 KCl + 8 MnCl_2 + 5 H_3AsO_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 HCl | 24 | -24 KMnO_4 | 8 | -8 AsH_3 | 5 | -5 H_2O | 12 | 12 KCl | 8 | 8 MnCl_2 | 8 | 8 H_3AsO_4 | 5 | 5 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 | 24 | -24 | -1/24 (Δ[HCl])/(Δt) KMnO_4 | 8 | -8 | -1/8 (Δ[KMnO4])/(Δt) AsH_3 | 5 | -5 | -1/5 (Δ[AsH3])/(Δt) H_2O | 12 | 12 | 1/12 (Δ[H2O])/(Δt) KCl | 8 | 8 | 1/8 (Δ[KCl])/(Δt) MnCl_2 | 8 | 8 | 1/8 (Δ[MnCl2])/(Δt) H_3AsO_4 | 5 | 5 | 1/5 (Δ[H3AsO4])/(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 = -1/24 (Δ[HCl])/(Δt) = -1/8 (Δ[KMnO4])/(Δt) = -1/5 (Δ[AsH3])/(Δt) = 1/12 (Δ[H2O])/(Δt) = 1/8 (Δ[KCl])/(Δt) = 1/8 (Δ[MnCl2])/(Δt) = 1/5 (Δ[H3AsO4])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen chloride | potassium permanganate | arsine | water | potassium chloride | manganese(II) chloride | arsenic acid, solid formula | HCl | KMnO_4 | AsH_3 | H_2O | KCl | MnCl_2 | H_3AsO_4 Hill formula | ClH | KMnO_4 | AsH_3 | H_2O | ClK | Cl_2Mn | AsH_3O_4 name | hydrogen chloride | potassium permanganate | arsine | water | potassium chloride | manganese(II) chloride | arsenic acid, solid IUPAC name | hydrogen chloride | potassium permanganate | arsane | water | potassium chloride | dichloromanganese | arsoric acid