KH2PO4 = H2O + KPO3

KH_2PO_4 potassium dihydrogen phosphate ⟶ H_2O water + KPO3

Balance the chemical equation algebraically: KH_2PO_4 ⟶ H_2O + KPO3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 KH_2PO_4 ⟶ c_2 H_2O + c_3 KPO3 Set the number of atoms in the reactants equal to the number of atoms in the products for H, K, O and P: H: | 2 c_1 = 2 c_2 K: | c_1 = c_3 O: | 4 c_1 = c_2 + 3 c_3 P: | c_1 = 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 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | KH_2PO_4 ⟶ H_2O + KPO3

⟶ + KPO3

potassium dihydrogen phosphate ⟶ water + KPO3

Construct the equilibrium constant, K, expression for: KH_2PO_4 ⟶ H_2O + KPO3 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: KH_2PO_4 ⟶ H_2O + KPO3 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 KH_2PO_4 | 1 | -1 H_2O | 1 | 1 KPO3 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression KH_2PO_4 | 1 | -1 | ([KH2PO4])^(-1) H_2O | 1 | 1 | [H2O] KPO3 | 1 | 1 | [KPO3] 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 = ([KH2PO4])^(-1) [H2O] [KPO3] = ([H2O] [KPO3])/([KH2PO4])

Construct the rate of reaction expression for: KH_2PO_4 ⟶ H_2O + KPO3 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: KH_2PO_4 ⟶ H_2O + KPO3 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 KH_2PO_4 | 1 | -1 H_2O | 1 | 1 KPO3 | 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 KH_2PO_4 | 1 | -1 | -(Δ[KH2PO4])/(Δt) H_2O | 1 | 1 | (Δ[H2O])/(Δt) KPO3 | 1 | 1 | (Δ[KPO3])/(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[KH2PO4])/(Δt) = (Δ[H2O])/(Δt) = (Δ[KPO3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| potassium dihydrogen phosphate | water | KPO3 formula | KH_2PO_4 | H_2O | KPO3 Hill formula | H_2KO_4P | H_2O | KO3P name | potassium dihydrogen phosphate | water |

| potassium dihydrogen phosphate | water | KPO3 molar mass | 136.08 g/mol | 18.015 g/mol | 118.07 g/mol phase | solid (at STP) | liquid (at STP) | melting point | 252.6 °C | 0 °C | boiling point | | 99.9839 °C | density | 2.338 g/cm^3 | 1 g/cm^3 | surface tension | | 0.0728 N/m | dynamic viscosity | | 8.9×10^-4 Pa s (at 25 °C) | odor | | odorless |