H2S + Na2S = NaHS

H_2S hydrogen sulfide + Na_2S sodium sulfide ⟶ NaHS sodium bisulfide

Balance the chemical equation algebraically: H_2S + Na_2S ⟶ NaHS Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2S + c_2 Na_2S ⟶ c_3 NaHS 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 = c_3 S: | c_1 + c_2 = c_3 Na: | 2 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 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | H_2S + Na_2S ⟶ 2 NaHS

+ ⟶

hydrogen sulfide + sodium sulfide ⟶ sodium bisulfide

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

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

| hydrogen sulfide | sodium sulfide | sodium bisulfide formula | H_2S | Na_2S | NaHS Hill formula | H_2S | Na_2S_1 | HNaS name | hydrogen sulfide | sodium sulfide | sodium bisulfide IUPAC name | hydrogen sulfide | | sodium sulfanide

| hydrogen sulfide | sodium sulfide | sodium bisulfide molar mass | 34.08 g/mol | 78.04 g/mol | 56.06 g/mol phase | gas (at STP) | solid (at STP) | solid (at STP) melting point | -85 °C | 1172 °C | 43 °C boiling point | -60 °C | | density | 0.001393 g/cm^3 (at 25 °C) | 1.856 g/cm^3 | 1.79 g/cm^3 dynamic viscosity | 1.239×10^-5 Pa s (at 25 °C) | |