SO2 + Li2Se = Li2O + SSe2

SO_2 sulfur dioxide + Li_2Se lithium selenide ⟶ Li_2O lithium oxide + SSe2

Balance the chemical equation algebraically: SO_2 + Li_2Se ⟶ Li_2O + SSe2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 SO_2 + c_2 Li_2Se ⟶ c_3 Li_2O + c_4 SSe2 Set the number of atoms in the reactants equal to the number of atoms in the products for O, S, Li and Se: O: | 2 c_1 = c_3 S: | c_1 = c_4 Li: | 2 c_2 = 2 c_3 Se: | c_2 = 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 = 2 c_3 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | SO_2 + 2 Li_2Se ⟶ 2 Li_2O + SSe2

+ ⟶ + SSe2

sulfur dioxide + lithium selenide ⟶ lithium oxide + SSe2

Construct the equilibrium constant, K, expression for: SO_2 + Li_2Se ⟶ Li_2O + SSe2 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: SO_2 + 2 Li_2Se ⟶ 2 Li_2O + SSe2 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 SO_2 | 1 | -1 Li_2Se | 2 | -2 Li_2O | 2 | 2 SSe2 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression SO_2 | 1 | -1 | ([SO2])^(-1) Li_2Se | 2 | -2 | ([Li2Se])^(-2) Li_2O | 2 | 2 | ([Li2O])^2 SSe2 | 1 | 1 | [SSe2] 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 = ([SO2])^(-1) ([Li2Se])^(-2) ([Li2O])^2 [SSe2] = (([Li2O])^2 [SSe2])/([SO2] ([Li2Se])^2)

Construct the rate of reaction expression for: SO_2 + Li_2Se ⟶ Li_2O + SSe2 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: SO_2 + 2 Li_2Se ⟶ 2 Li_2O + SSe2 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 SO_2 | 1 | -1 Li_2Se | 2 | -2 Li_2O | 2 | 2 SSe2 | 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 SO_2 | 1 | -1 | -(Δ[SO2])/(Δt) Li_2Se | 2 | -2 | -1/2 (Δ[Li2Se])/(Δt) Li_2O | 2 | 2 | 1/2 (Δ[Li2O])/(Δt) SSe2 | 1 | 1 | (Δ[SSe2])/(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[SO2])/(Δt) = -1/2 (Δ[Li2Se])/(Δt) = 1/2 (Δ[Li2O])/(Δt) = (Δ[SSe2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| sulfur dioxide | lithium selenide | lithium oxide | SSe2 formula | SO_2 | Li_2Se | Li_2O | SSe2 Hill formula | O_2S | Li_2Se | Li_2O | SSe2 name | sulfur dioxide | lithium selenide | lithium oxide | IUPAC name | sulfur dioxide | | dilithium oxygen(-2) anion |

| sulfur dioxide | lithium selenide | lithium oxide | SSe2 molar mass | 64.06 g/mol | 92.9 g/mol | 29.9 g/mol | 190 g/mol phase | gas (at STP) | | | melting point | -73 °C | | | boiling point | -10 °C | | | density | 0.002619 g/cm^3 (at 25 °C) | | 2.013 g/cm^3 | surface tension | 0.02859 N/m | | | dynamic viscosity | 1.282×10^-5 Pa s (at 25 °C) | | |