H2S + Sn = H2 + SnS2

H_2S hydrogen sulfide + Sn white tin ⟶ H_2 hydrogen + SnS_2 tin(IV) sulfide

Balance the chemical equation algebraically: H_2S + Sn ⟶ H_2 + SnS_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2S + c_2 Sn ⟶ c_3 H_2 + c_4 SnS_2 Set the number of atoms in the reactants equal to the number of atoms in the products for H, S and Sn: H: | 2 c_1 = 2 c_3 S: | c_1 = 2 c_4 Sn: | 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 1 c_3 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 H_2S + Sn ⟶ 2 H_2 + SnS_2

+ ⟶ +

hydrogen sulfide + white tin ⟶ hydrogen + tin(IV) sulfide

Construct the equilibrium constant, K, expression for: H_2S + Sn ⟶ H_2 + SnS_2 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 H_2S + Sn ⟶ 2 H_2 + SnS_2 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_2S | 2 | -2 Sn | 1 | -1 H_2 | 2 | 2 SnS_2 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2S | 2 | -2 | ([H2S])^(-2) Sn | 1 | -1 | ([Sn])^(-1) H_2 | 2 | 2 | ([H2])^2 SnS_2 | 1 | 1 | [SnS2] 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 = ([H2S])^(-2) ([Sn])^(-1) ([H2])^2 [SnS2] = (([H2])^2 [SnS2])/(([H2S])^2 [Sn])

Construct the rate of reaction expression for: H_2S + Sn ⟶ H_2 + SnS_2 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 H_2S + Sn ⟶ 2 H_2 + SnS_2 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_2S | 2 | -2 Sn | 1 | -1 H_2 | 2 | 2 SnS_2 | 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_2S | 2 | -2 | -1/2 (Δ[H2S])/(Δt) Sn | 1 | -1 | -(Δ[Sn])/(Δt) H_2 | 2 | 2 | 1/2 (Δ[H2])/(Δt) SnS_2 | 1 | 1 | (Δ[SnS2])/(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[H2S])/(Δt) = -(Δ[Sn])/(Δt) = 1/2 (Δ[H2])/(Δt) = (Δ[SnS2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen sulfide | white tin | hydrogen | tin(IV) sulfide formula | H_2S | Sn | H_2 | SnS_2 Hill formula | H_2S | Sn | H_2 | S_2Sn name | hydrogen sulfide | white tin | hydrogen | tin(IV) sulfide IUPAC name | hydrogen sulfide | tin | molecular hydrogen | tin(+4) cation disulfide

| hydrogen sulfide | white tin | hydrogen | tin(IV) sulfide molar mass | 34.08 g/mol | 118.71 g/mol | 2.016 g/mol | 182.8 g/mol phase | gas (at STP) | solid (at STP) | gas (at STP) | solid (at STP) melting point | -85 °C | 231.9 °C | -259.2 °C | 600 °C boiling point | -60 °C | 2602 °C | -252.8 °C | density | 0.001393 g/cm^3 (at 25 °C) | 7.31 g/cm^3 | 8.99×10^-5 g/cm^3 (at 0 °C) | 4.5 g/cm^3 solubility in water | | insoluble | | insoluble dynamic viscosity | 1.239×10^-5 Pa s (at 25 °C) | 0.001 Pa s (at 600 °C) | 8.9×10^-6 Pa s (at 25 °C) | odor | | odorless | odorless |