KOH + ZnO = Zn(OH)2 + K2O

KOH potassium hydroxide + ZnO zinc oxide ⟶ Zn(OH)_2 zinc hydroxide + K_2O potassium oxide

Balance the chemical equation algebraically: KOH + ZnO ⟶ Zn(OH)_2 + K_2O Add stoichiometric coefficients, c_i, to the reactants and products: c_1 KOH + c_2 ZnO ⟶ c_3 Zn(OH)_2 + c_4 K_2O Set the number of atoms in the reactants equal to the number of atoms in the products for H, K, O and Zn: H: | c_1 = 2 c_3 K: | c_1 = 2 c_4 O: | c_1 + c_2 = 2 c_3 + 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 1 c_3 = 1 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 KOH + ZnO ⟶ Zn(OH)_2 + K_2O

+ ⟶ +

potassium hydroxide + zinc oxide ⟶ zinc hydroxide + potassium oxide

Construct the equilibrium constant, K, expression for: KOH + ZnO ⟶ Zn(OH)_2 + K_2O 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 KOH + ZnO ⟶ Zn(OH)_2 + K_2O 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 KOH | 2 | -2 ZnO | 1 | -1 Zn(OH)_2 | 1 | 1 K_2O | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression KOH | 2 | -2 | ([KOH])^(-2) ZnO | 1 | -1 | ([ZnO])^(-1) Zn(OH)_2 | 1 | 1 | [Zn(OH)2] K_2O | 1 | 1 | [K2O] 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 = ([KOH])^(-2) ([ZnO])^(-1) [Zn(OH)2] [K2O] = ([Zn(OH)2] [K2O])/(([KOH])^2 [ZnO])

Construct the rate of reaction expression for: KOH + ZnO ⟶ Zn(OH)_2 + K_2O 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 KOH + ZnO ⟶ Zn(OH)_2 + K_2O 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 KOH | 2 | -2 ZnO | 1 | -1 Zn(OH)_2 | 1 | 1 K_2O | 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 KOH | 2 | -2 | -1/2 (Δ[KOH])/(Δt) ZnO | 1 | -1 | -(Δ[ZnO])/(Δt) Zn(OH)_2 | 1 | 1 | (Δ[Zn(OH)2])/(Δt) K_2O | 1 | 1 | (Δ[K2O])/(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[KOH])/(Δt) = -(Δ[ZnO])/(Δt) = (Δ[Zn(OH)2])/(Δt) = (Δ[K2O])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| potassium hydroxide | zinc oxide | zinc hydroxide | potassium oxide formula | KOH | ZnO | Zn(OH)_2 | K_2O Hill formula | HKO | OZn | H_2O_2Zn | K_2O name | potassium hydroxide | zinc oxide | zinc hydroxide | potassium oxide IUPAC name | potassium hydroxide | oxozinc | zinc dihydroxide | dipotassium oxygen(2-)

| potassium hydroxide | zinc oxide | zinc hydroxide | potassium oxide molar mass | 56.105 g/mol | 81.38 g/mol | 99.39 g/mol | 94.196 g/mol phase | solid (at STP) | solid (at STP) | | melting point | 406 °C | 1975 °C | | boiling point | 1327 °C | 2360 °C | | density | 2.044 g/cm^3 | 5.6 g/cm^3 | | solubility in water | soluble | | | dynamic viscosity | 0.001 Pa s (at 550 °C) | | | odor | | odorless | |