H2S + Na = H2 + Na2S

H_2S hydrogen sulfide + Na sodium ⟶ H_2 hydrogen + Na_2S sodium sulfide

Balance the chemical equation algebraically: H_2S + Na ⟶ H_2 + Na_2S Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2S + c_2 Na ⟶ c_3 H_2 + c_4 Na_2S Set the number of atoms in the reactants equal to the number of atoms in the products for H, S and Na: H: | 2 c_1 = 2 c_3 S: | c_1 = c_4 Na: | 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 = 1 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | H_2S + 2 Na ⟶ H_2 + Na_2S

+ ⟶ +

hydrogen sulfide + sodium ⟶ hydrogen + sodium sulfide

| hydrogen sulfide | sodium | hydrogen | sodium sulfide molecular enthalpy | -20.6 kJ/mol | 0 kJ/mol | 0 kJ/mol | -364.8 kJ/mol total enthalpy | -20.6 kJ/mol | 0 kJ/mol | 0 kJ/mol | -364.8 kJ/mol | H_initial = -20.6 kJ/mol | | H_final = -364.8 kJ/mol | ΔH_rxn^0 | -364.8 kJ/mol - -20.6 kJ/mol = -344.2 kJ/mol (exothermic) | | |

Construct the equilibrium constant, K, expression for: H_2S + Na ⟶ H_2 + Na_2S 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_2S + 2 Na ⟶ H_2 + Na_2S 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 | 1 | -1 Na | 2 | -2 H_2 | 1 | 1 Na_2S | 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 | 1 | -1 | ([H2S])^(-1) Na | 2 | -2 | ([Na])^(-2) H_2 | 1 | 1 | [H2] Na_2S | 1 | 1 | [Na2S] 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])^(-1) ([Na])^(-2) [H2] [Na2S] = ([H2] [Na2S])/([H2S] ([Na])^2)

Construct the rate of reaction expression for: H_2S + Na ⟶ H_2 + Na_2S 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_2S + 2 Na ⟶ H_2 + Na_2S 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 | 1 | -1 Na | 2 | -2 H_2 | 1 | 1 Na_2S | 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 | 1 | -1 | -(Δ[H2S])/(Δt) Na | 2 | -2 | -1/2 (Δ[Na])/(Δt) H_2 | 1 | 1 | (Δ[H2])/(Δt) Na_2S | 1 | 1 | (Δ[Na2S])/(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[H2S])/(Δt) = -1/2 (Δ[Na])/(Δt) = (Δ[H2])/(Δt) = (Δ[Na2S])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen sulfide | sodium | hydrogen | sodium sulfide formula | H_2S | Na | H_2 | Na_2S Hill formula | H_2S | Na | H_2 | Na_2S_1 name | hydrogen sulfide | sodium | hydrogen | sodium sulfide IUPAC name | hydrogen sulfide | sodium | molecular hydrogen |

| hydrogen sulfide | sodium | hydrogen | sodium sulfide molar mass | 34.08 g/mol | 22.98976928 g/mol | 2.016 g/mol | 78.04 g/mol phase | gas (at STP) | solid (at STP) | gas (at STP) | solid (at STP) melting point | -85 °C | 97.8 °C | -259.2 °C | 1172 °C boiling point | -60 °C | 883 °C | -252.8 °C | density | 0.001393 g/cm^3 (at 25 °C) | 0.968 g/cm^3 | 8.99×10^-5 g/cm^3 (at 0 °C) | 1.856 g/cm^3 solubility in water | | decomposes | | dynamic viscosity | 1.239×10^-5 Pa s (at 25 °C) | 1.413×10^-5 Pa s (at 527 °C) | 8.9×10^-6 Pa s (at 25 °C) | odor | | | odorless |