K2S2O5 = SO2 + K2SO3

K_2S_2O_5 potassium metabisulfite ⟶ SO_2 sulfur dioxide + K_2SO_3 potassium sulfite

Balance the chemical equation algebraically: K_2S_2O_5 ⟶ SO_2 + K_2SO_3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 K_2S_2O_5 ⟶ c_2 SO_2 + c_3 K_2SO_3 Set the number of atoms in the reactants equal to the number of atoms in the products for K, O and S: K: | 2 c_1 = 2 c_3 O: | 5 c_1 = 2 c_2 + 3 c_3 S: | 2 c_1 = 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: | | K_2S_2O_5 ⟶ SO_2 + K_2SO_3

⟶ +

potassium metabisulfite ⟶ sulfur dioxide + potassium sulfite

Construct the equilibrium constant, K, expression for: K_2S_2O_5 ⟶ SO_2 + K_2SO_3 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: K_2S_2O_5 ⟶ SO_2 + K_2SO_3 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 K_2S_2O_5 | 1 | -1 SO_2 | 1 | 1 K_2SO_3 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression K_2S_2O_5 | 1 | -1 | ([K2S2O5])^(-1) SO_2 | 1 | 1 | [SO2] K_2SO_3 | 1 | 1 | [K2SO3] 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 = ([K2S2O5])^(-1) [SO2] [K2SO3] = ([SO2] [K2SO3])/([K2S2O5])

Construct the rate of reaction expression for: K_2S_2O_5 ⟶ SO_2 + K_2SO_3 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: K_2S_2O_5 ⟶ SO_2 + K_2SO_3 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 K_2S_2O_5 | 1 | -1 SO_2 | 1 | 1 K_2SO_3 | 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 K_2S_2O_5 | 1 | -1 | -(Δ[K2S2O5])/(Δt) SO_2 | 1 | 1 | (Δ[SO2])/(Δt) K_2SO_3 | 1 | 1 | (Δ[K2SO3])/(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[K2S2O5])/(Δt) = (Δ[SO2])/(Δt) = (Δ[K2SO3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| potassium metabisulfite | sulfur dioxide | potassium sulfite formula | K_2S_2O_5 | SO_2 | K_2SO_3 Hill formula | K_2O_5S_2 | O_2S | K_2O_3S name | potassium metabisulfite | sulfur dioxide | potassium sulfite IUPAC name | | sulfur dioxide | dipotassium sulfite

| potassium metabisulfite | sulfur dioxide | potassium sulfite molar mass | 222.3 g/mol | 64.06 g/mol | 158.25 g/mol phase | solid (at STP) | gas (at STP) | melting point | 190 °C | -73 °C | boiling point | | -10 °C | density | 1.2 g/cm^3 | 0.002619 g/cm^3 (at 25 °C) | surface tension | | 0.02859 N/m | dynamic viscosity | | 1.282×10^-5 Pa s (at 25 °C) |