NaOH + H3PO4 = Na(PO4) + H3OH

NaOH sodium hydroxide + H_3PO_4 phosphoric acid ⟶ NaPO4 + H3OH

Balance the chemical equation algebraically: NaOH + H_3PO_4 ⟶ NaPO4 + H3OH Add stoichiometric coefficients, c_i, to the reactants and products: c_1 NaOH + c_2 H_3PO_4 ⟶ c_3 NaPO4 + c_4 H3OH Set the number of atoms in the reactants equal to the number of atoms in the products for H, Na, O and P: H: | c_1 + 3 c_2 = 4 c_4 Na: | c_1 = c_3 O: | c_1 + 4 c_2 = 4 c_3 + c_4 P: | 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: | | NaOH + H_3PO_4 ⟶ NaPO4 + H3OH

+ ⟶ NaPO4 + H3OH

sodium hydroxide + phosphoric acid ⟶ NaPO4 + H3OH

Construct the equilibrium constant, K, expression for: NaOH + H_3PO_4 ⟶ NaPO4 + H3OH 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: NaOH + H_3PO_4 ⟶ NaPO4 + H3OH 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 | 1 | -1 H_3PO_4 | 1 | -1 NaPO4 | 1 | 1 H3OH | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression NaOH | 1 | -1 | ([NaOH])^(-1) H_3PO_4 | 1 | -1 | ([H3PO4])^(-1) NaPO4 | 1 | 1 | [NaPO4] H3OH | 1 | 1 | [H3OH] 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])^(-1) ([H3PO4])^(-1) [NaPO4] [H3OH] = ([NaPO4] [H3OH])/([NaOH] [H3PO4])

Construct the rate of reaction expression for: NaOH + H_3PO_4 ⟶ NaPO4 + H3OH 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: NaOH + H_3PO_4 ⟶ NaPO4 + H3OH 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 | 1 | -1 H_3PO_4 | 1 | -1 NaPO4 | 1 | 1 H3OH | 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 | 1 | -1 | -(Δ[NaOH])/(Δt) H_3PO_4 | 1 | -1 | -(Δ[H3PO4])/(Δt) NaPO4 | 1 | 1 | (Δ[NaPO4])/(Δt) H3OH | 1 | 1 | (Δ[H3OH])/(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[NaOH])/(Δt) = -(Δ[H3PO4])/(Δt) = (Δ[NaPO4])/(Δt) = (Δ[H3OH])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| sodium hydroxide | phosphoric acid | NaPO4 | H3OH formula | NaOH | H_3PO_4 | NaPO4 | H3OH Hill formula | HNaO | H_3O_4P | NaO4P | H4O name | sodium hydroxide | phosphoric acid | |

| sodium hydroxide | phosphoric acid | NaPO4 | H3OH molar mass | 39.997 g/mol | 97.994 g/mol | 117.96 g/mol | 20.031 g/mol phase | solid (at STP) | liquid (at STP) | | melting point | 323 °C | 42.4 °C | | boiling point | 1390 °C | 158 °C | | density | 2.13 g/cm^3 | 1.685 g/cm^3 | | solubility in water | soluble | very soluble | | surface tension | 0.07435 N/m | | | dynamic viscosity | 0.004 Pa s (at 350 °C) | | | odor | | odorless | |