Mg + ZnS = Zn + MgS

Mg magnesium + ZnS zinc sulfide ⟶ Zn zinc + MgS magnesium sulfide

Balance the chemical equation algebraically: Mg + ZnS ⟶ Zn + MgS Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Mg + c_2 ZnS ⟶ c_3 Zn + c_4 MgS Set the number of atoms in the reactants equal to the number of atoms in the products for Mg, S and Zn: Mg: | c_1 = c_4 S: | c_2 = c_4 Zn: | 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 = 1 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | Mg + ZnS ⟶ Zn + MgS

+ ⟶ +

magnesium + zinc sulfide ⟶ zinc + magnesium sulfide

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

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

| magnesium | zinc sulfide | zinc | magnesium sulfide formula | Mg | ZnS | Zn | MgS Hill formula | Mg | SZn | Zn | MgS name | magnesium | zinc sulfide | zinc | magnesium sulfide IUPAC name | magnesium | thioxozinc | zinc |

| magnesium | zinc sulfide | zinc | magnesium sulfide molar mass | 24.305 g/mol | 97.44 g/mol | 65.38 g/mol | 56.36 g/mol phase | solid (at STP) | solid (at STP) | solid (at STP) | melting point | 648 °C | 1064 °C | 420 °C | 2226 °C boiling point | 1090 °C | | 907 °C | density | 1.738 g/cm^3 | 4.1 g/cm^3 | 7.14 g/cm^3 | 2.68 g/cm^3 solubility in water | reacts | | insoluble | reacts odor | | | odorless |