H2SO3 + Zn(OH)2 = H2O + ZnSO3

H_2SO_3 sulfurous acid + Zn(OH)_2 zinc hydroxide ⟶ H_2O water + ZnSO3

Balance the chemical equation algebraically: H_2SO_3 + Zn(OH)_2 ⟶ H_2O + ZnSO3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2SO_3 + c_2 Zn(OH)_2 ⟶ c_3 H_2O + c_4 ZnSO3 Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, S and Zn: H: | 2 c_1 + 2 c_2 = 2 c_3 O: | 3 c_1 + 2 c_2 = c_3 + 3 c_4 S: | c_1 = c_4 Zn: | c_2 = c_4 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 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | H_2SO_3 + Zn(OH)_2 ⟶ 2 H_2O + ZnSO3

+ ⟶ + ZnSO3

sulfurous acid + zinc hydroxide ⟶ water + ZnSO3

Construct the equilibrium constant, K, expression for: H_2SO_3 + Zn(OH)_2 ⟶ H_2O + ZnSO3 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: H_2SO_3 + Zn(OH)_2 ⟶ 2 H_2O + ZnSO3 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 H_2SO_3 | 1 | -1 Zn(OH)_2 | 1 | -1 H_2O | 2 | 2 ZnSO3 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2SO_3 | 1 | -1 | ([H2SO3])^(-1) Zn(OH)_2 | 1 | -1 | ([Zn(OH)2])^(-1) H_2O | 2 | 2 | ([H2O])^2 ZnSO3 | 1 | 1 | [ZnSO3] 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 = ([H2SO3])^(-1) ([Zn(OH)2])^(-1) ([H2O])^2 [ZnSO3] = (([H2O])^2 [ZnSO3])/([H2SO3] [Zn(OH)2])

Construct the rate of reaction expression for: H_2SO_3 + Zn(OH)_2 ⟶ H_2O + ZnSO3 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: H_2SO_3 + Zn(OH)_2 ⟶ 2 H_2O + ZnSO3 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 H_2SO_3 | 1 | -1 Zn(OH)_2 | 1 | -1 H_2O | 2 | 2 ZnSO3 | 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 H_2SO_3 | 1 | -1 | -(Δ[H2SO3])/(Δt) Zn(OH)_2 | 1 | -1 | -(Δ[Zn(OH)2])/(Δt) H_2O | 2 | 2 | 1/2 (Δ[H2O])/(Δt) ZnSO3 | 1 | 1 | (Δ[ZnSO3])/(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[H2SO3])/(Δt) = -(Δ[Zn(OH)2])/(Δt) = 1/2 (Δ[H2O])/(Δt) = (Δ[ZnSO3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| sulfurous acid | zinc hydroxide | water | ZnSO3 formula | H_2SO_3 | Zn(OH)_2 | H_2O | ZnSO3 Hill formula | H_2O_3S | H_2O_2Zn | H_2O | O3SZn name | sulfurous acid | zinc hydroxide | water | IUPAC name | sulfurous acid | zinc dihydroxide | water |

| sulfurous acid | zinc hydroxide | water | ZnSO3 molar mass | 82.07 g/mol | 99.39 g/mol | 18.015 g/mol | 145.4 g/mol phase | | | liquid (at STP) | melting point | | | 0 °C | boiling point | | | 99.9839 °C | density | 1.03 g/cm^3 | | 1 g/cm^3 | solubility in water | very soluble | | | surface tension | | | 0.0728 N/m | dynamic viscosity | | | 8.9×10^-4 Pa s (at 25 °C) | odor | | | odorless |