ZnS = S + Zn

ZnS zinc sulfide ⟶ S mixed sulfur + Zn zinc

Balance the chemical equation algebraically: ZnS ⟶ S + Zn Add stoichiometric coefficients, c_i, to the reactants and products: c_1 ZnS ⟶ c_2 S + c_3 Zn Set the number of atoms in the reactants equal to the number of atoms in the products for S and Zn: S: | c_1 = c_2 Zn: | c_1 = 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: | | ZnS ⟶ S + Zn

⟶ +

zinc sulfide ⟶ mixed sulfur + zinc

Construct the equilibrium constant, K, expression for: ZnS ⟶ S + Zn 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: ZnS ⟶ S + Zn 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 ZnS | 1 | -1 S | 1 | 1 Zn | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression ZnS | 1 | -1 | ([ZnS])^(-1) S | 1 | 1 | [S] Zn | 1 | 1 | [Zn] 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 = ([ZnS])^(-1) [S] [Zn] = ([S] [Zn])/([ZnS])

Construct the rate of reaction expression for: ZnS ⟶ S + Zn 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: ZnS ⟶ S + Zn 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 ZnS | 1 | -1 S | 1 | 1 Zn | 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 ZnS | 1 | -1 | -(Δ[ZnS])/(Δt) S | 1 | 1 | (Δ[S])/(Δt) Zn | 1 | 1 | (Δ[Zn])/(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[ZnS])/(Δt) = (Δ[S])/(Δt) = (Δ[Zn])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| zinc sulfide | mixed sulfur | zinc formula | ZnS | S | Zn Hill formula | SZn | S | Zn name | zinc sulfide | mixed sulfur | zinc IUPAC name | thioxozinc | sulfur | zinc

| zinc sulfide | mixed sulfur | zinc molar mass | 97.44 g/mol | 32.06 g/mol | 65.38 g/mol phase | solid (at STP) | solid (at STP) | solid (at STP) melting point | 1064 °C | 112.8 °C | 420 °C boiling point | | 444.7 °C | 907 °C density | 4.1 g/cm^3 | 2.07 g/cm^3 | 7.14 g/cm^3 solubility in water | | | insoluble odor | | | odorless