NH3 + OH = H2O + NH2

NH_3 ammonia + (OH)^- hydroxide anion ⟶ H_2O water + (NH_2)^- amide anion

Balance the chemical equation algebraically: NH_3 + (OH)^- ⟶ H_2O + (NH_2)^- Add stoichiometric coefficients, c_i, to the reactants and products: c_1 NH_3 + c_2 OH^- ⟶ c_3 H_2O + c_4 (NH_2)^- Set the number of atoms and the charges in the reactants equal to the number of atoms and the charges in the products for H, N and O: H: | 3 c_1 + c_2 = 2 c_3 + 2 c_4 N: | c_1 = c_4 O: | c_2 = c_3 Charges: | -c_2 = -c_4 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: | | NH_3 + OH^- ⟶ H_2O + (NH_2)^-

+ ⟶ +

ammonia + hydroxide anion ⟶ water + amide anion

Construct the equilibrium constant, K, expression for: NH_3 + (OH)^- ⟶ H_2O + (NH_2)^- 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: NH_3 + OH^- ⟶ H_2O + (NH_2)^- 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 NH_3 | 1 | -1 OH^- | 1 | -1 H_2O | 1 | 1 (NH_2)^- | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression NH_3 | 1 | -1 | ([NH3])^(-1) OH^- | 1 | -1 | ([OH-1])^(-1) H_2O | 1 | 1 | [H2O] (NH_2)^- | 1 | 1 | [NH2-1] 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 = ([NH3])^(-1) ([OH-1])^(-1) [H2O] [NH2-1] = ([H2O] [NH2-1])/([NH3] [OH-1])

Construct the rate of reaction expression for: NH_3 + (OH)^- ⟶ H_2O + (NH_2)^- 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: NH_3 + OH^- ⟶ H_2O + (NH_2)^- 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 NH_3 | 1 | -1 OH^- | 1 | -1 H_2O | 1 | 1 (NH_2)^- | 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 NH_3 | 1 | -1 | -(Δ[NH3])/(Δt) OH^- | 1 | -1 | -(Δ[OH-1])/(Δt) H_2O | 1 | 1 | (Δ[H2O])/(Δt) (NH_2)^- | 1 | 1 | (Δ[NH2-1])/(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[NH3])/(Δt) = -(Δ[OH-1])/(Δt) = (Δ[H2O])/(Δt) = (Δ[NH2-1])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| ammonia | hydroxide anion | water | amide anion formula | NH_3 | (OH)^- | H_2O | (NH_2)^- Hill formula | H_3N | | H_2O | name | ammonia | hydroxide anion | water | amide anion

| ammonia | hydroxide anion | water | amide anion molar mass | 17.031 g/mol | 17.008 g/mol | 18.015 g/mol | 16.024 g/mol phase | gas (at STP) | | liquid (at STP) | melting point | -77.73 °C | | 0 °C | boiling point | -33.33 °C | | 99.9839 °C | density | 6.96×10^-4 g/cm^3 (at 25 °C) | | 1 g/cm^3 | surface tension | 0.0234 N/m | | 0.0728 N/m | dynamic viscosity | 1.009×10^-5 Pa s (at 25 °C) | | 8.9×10^-4 Pa s (at 25 °C) | odor | | | odorless |