HCl + K3PO4 = KCl + H3PO4

HCl hydrogen chloride + K3PO4 ⟶ KCl potassium chloride + H_3PO_4 phosphoric acid

Balance the chemical equation algebraically: HCl + K3PO4 ⟶ KCl + H_3PO_4 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HCl + c_2 K3PO4 ⟶ c_3 KCl + c_4 H_3PO_4 Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, H, K, P and O: Cl: | c_1 = c_3 H: | c_1 = 3 c_4 K: | 3 c_2 = c_3 P: | c_2 = c_4 O: | 4 c_2 = 4 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 3 c_2 = 1 c_3 = 3 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 HCl + K3PO4 ⟶ 3 KCl + H_3PO_4

+ K3PO4 ⟶ +

hydrogen chloride + K3PO4 ⟶ potassium chloride + phosphoric acid

Construct the equilibrium constant, K, expression for: HCl + K3PO4 ⟶ KCl + H_3PO_4 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: 3 HCl + K3PO4 ⟶ 3 KCl + H_3PO_4 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 HCl | 3 | -3 K3PO4 | 1 | -1 KCl | 3 | 3 H_3PO_4 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HCl | 3 | -3 | ([HCl])^(-3) K3PO4 | 1 | -1 | ([K3PO4])^(-1) KCl | 3 | 3 | ([KCl])^3 H_3PO_4 | 1 | 1 | [H3PO4] 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 = ([HCl])^(-3) ([K3PO4])^(-1) ([KCl])^3 [H3PO4] = (([KCl])^3 [H3PO4])/(([HCl])^3 [K3PO4])

Construct the rate of reaction expression for: HCl + K3PO4 ⟶ KCl + H_3PO_4 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: 3 HCl + K3PO4 ⟶ 3 KCl + H_3PO_4 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 HCl | 3 | -3 K3PO4 | 1 | -1 KCl | 3 | 3 H_3PO_4 | 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 HCl | 3 | -3 | -1/3 (Δ[HCl])/(Δt) K3PO4 | 1 | -1 | -(Δ[K3PO4])/(Δt) KCl | 3 | 3 | 1/3 (Δ[KCl])/(Δt) H_3PO_4 | 1 | 1 | (Δ[H3PO4])/(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 = -1/3 (Δ[HCl])/(Δt) = -(Δ[K3PO4])/(Δt) = 1/3 (Δ[KCl])/(Δt) = (Δ[H3PO4])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen chloride | K3PO4 | potassium chloride | phosphoric acid formula | HCl | K3PO4 | KCl | H_3PO_4 Hill formula | ClH | K3O4P | ClK | H_3O_4P name | hydrogen chloride | | potassium chloride | phosphoric acid

| hydrogen chloride | K3PO4 | potassium chloride | phosphoric acid molar mass | 36.46 g/mol | 212.26 g/mol | 74.55 g/mol | 97.994 g/mol phase | gas (at STP) | | solid (at STP) | liquid (at STP) melting point | -114.17 °C | | 770 °C | 42.4 °C boiling point | -85 °C | | 1420 °C | 158 °C density | 0.00149 g/cm^3 (at 25 °C) | | 1.98 g/cm^3 | 1.685 g/cm^3 solubility in water | miscible | | soluble | very soluble odor | | | odorless | odorless