NaOH = H2O + Na2O

NaOH (sodium hydroxide) ⟶ H_2O (water) + Na_2O (sodium oxide)

Balance the chemical equation algebraically: NaOH ⟶ H_2O + Na_2O Add stoichiometric coefficients, c_i, to the reactants and products: c_1 NaOH ⟶ c_2 H_2O + c_3 Na_2O Set the number of atoms in the reactants equal to the number of atoms in the products for H, Na and O: H: | c_1 = 2 c_2 Na: | c_1 = 2 c_3 O: | c_1 = 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 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 NaOH ⟶ H_2O + Na_2O

⟶ +

sodium hydroxide ⟶ water + sodium oxide

Construct the equilibrium constant, K, expression for: NaOH ⟶ H_2O + Na_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 NaOH ⟶ H_2O + Na_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 NaOH | 2 | -2 H_2O | 1 | 1 Na_2O | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression NaOH | 2 | -2 | ([NaOH])^(-2) H_2O | 1 | 1 | [H2O] Na_2O | 1 | 1 | [Na2O] 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 = ([NaOH])^(-2) [H2O] [Na2O] = ([H2O] [Na2O])/([NaOH])^2

Construct the rate of reaction expression for: NaOH ⟶ H_2O + Na_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 NaOH ⟶ H_2O + Na_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 NaOH | 2 | -2 H_2O | 1 | 1 Na_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 NaOH | 2 | -2 | -1/2 (Δ[NaOH])/(Δt) H_2O | 1 | 1 | (Δ[H2O])/(Δt) Na_2O | 1 | 1 | (Δ[Na2O])/(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[NaOH])/(Δt) = (Δ[H2O])/(Δt) = (Δ[Na2O])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| sodium hydroxide | water | sodium oxide formula | NaOH | H_2O | Na_2O Hill formula | HNaO | H_2O | Na_2O name | sodium hydroxide | water | sodium oxide IUPAC name | sodium hydroxide | water | disodium oxygen(-2) anion

| sodium hydroxide | water | sodium oxide molar mass | 39.997 g/mol | 18.015 g/mol | 61.979 g/mol phase | solid (at STP) | liquid (at STP) | melting point | 323 °C | 0 °C | boiling point | 1390 °C | 99.9839 °C | density | 2.13 g/cm^3 | 1 g/cm^3 | 2.27 g/cm^3 solubility in water | soluble | | surface tension | 0.07435 N/m | 0.0728 N/m | dynamic viscosity | 0.004 Pa s (at 350 °C) | 8.9×10^-4 Pa s (at 25 °C) | odor | | odorless |