Input interpretation
H_2O water + K3PO4 ⟶ O_2 oxygen + H_2 hydrogen + KOH potassium hydroxide + H_3PO_4 phosphoric acid
Balanced equation
Balance the chemical equation algebraically: H_2O + K3PO4 ⟶ O_2 + H_2 + KOH + H_3PO_4 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O + c_2 K3PO4 ⟶ c_3 O_2 + c_4 H_2 + c_5 KOH + c_6 H_3PO_4 Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, K and P: H: | 2 c_1 = 2 c_4 + c_5 + 3 c_6 O: | c_1 + 4 c_2 = 2 c_3 + c_5 + 4 c_6 K: | 3 c_2 = c_5 P: | c_2 = c_6 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_2 = 1 c_3 = c_1/2 - 3/2 c_4 = c_1 - 3 c_5 = 3 c_6 = 1 The resulting system of equations is still underdetermined, so an additional coefficient must be set arbitrarily. Set c_1 = 5 and solve for the remaining coefficients: c_1 = 5 c_2 = 1 c_3 = 1 c_4 = 2 c_5 = 3 c_6 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 5 H_2O + K3PO4 ⟶ O_2 + 2 H_2 + 3 KOH + H_3PO_4
Structures
+ K3PO4 ⟶ + + +
Names
water + K3PO4 ⟶ oxygen + hydrogen + potassium hydroxide + phosphoric acid
Equilibrium constant
Construct the equilibrium constant, K, expression for: H_2O + K3PO4 ⟶ O_2 + H_2 + KOH + 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: 5 H_2O + K3PO4 ⟶ O_2 + 2 H_2 + 3 KOH + 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 H_2O | 5 | -5 K3PO4 | 1 | -1 O_2 | 1 | 1 H_2 | 2 | 2 KOH | 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 H_2O | 5 | -5 | ([H2O])^(-5) K3PO4 | 1 | -1 | ([K3PO4])^(-1) O_2 | 1 | 1 | [O2] H_2 | 2 | 2 | ([H2])^2 KOH | 3 | 3 | ([KOH])^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 = ([H2O])^(-5) ([K3PO4])^(-1) [O2] ([H2])^2 ([KOH])^3 [H3PO4] = ([O2] ([H2])^2 ([KOH])^3 [H3PO4])/(([H2O])^5 [K3PO4])
Rate of reaction
Construct the rate of reaction expression for: H_2O + K3PO4 ⟶ O_2 + H_2 + KOH + 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: 5 H_2O + K3PO4 ⟶ O_2 + 2 H_2 + 3 KOH + 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 H_2O | 5 | -5 K3PO4 | 1 | -1 O_2 | 1 | 1 H_2 | 2 | 2 KOH | 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 H_2O | 5 | -5 | -1/5 (Δ[H2O])/(Δt) K3PO4 | 1 | -1 | -(Δ[K3PO4])/(Δt) O_2 | 1 | 1 | (Δ[O2])/(Δt) H_2 | 2 | 2 | 1/2 (Δ[H2])/(Δt) KOH | 3 | 3 | 1/3 (Δ[KOH])/(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 = -1/5 (Δ[H2O])/(Δt) = -(Δ[K3PO4])/(Δt) = (Δ[O2])/(Δt) = 1/2 (Δ[H2])/(Δt) = 1/3 (Δ[KOH])/(Δt) = (Δ[H3PO4])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)
Chemical names and formulas
| water | K3PO4 | oxygen | hydrogen | potassium hydroxide | phosphoric acid formula | H_2O | K3PO4 | O_2 | H_2 | KOH | H_3PO_4 Hill formula | H_2O | K3O4P | O_2 | H_2 | HKO | H_3O_4P name | water | | oxygen | hydrogen | potassium hydroxide | phosphoric acid IUPAC name | water | | molecular oxygen | molecular hydrogen | potassium hydroxide | phosphoric acid
Substance properties
| water | K3PO4 | oxygen | hydrogen | potassium hydroxide | phosphoric acid molar mass | 18.015 g/mol | 212.26 g/mol | 31.998 g/mol | 2.016 g/mol | 56.105 g/mol | 97.994 g/mol phase | liquid (at STP) | | gas (at STP) | gas (at STP) | solid (at STP) | liquid (at STP) melting point | 0 °C | | -218 °C | -259.2 °C | 406 °C | 42.4 °C boiling point | 99.9839 °C | | -183 °C | -252.8 °C | 1327 °C | 158 °C density | 1 g/cm^3 | | 0.001429 g/cm^3 (at 0 °C) | 8.99×10^-5 g/cm^3 (at 0 °C) | 2.044 g/cm^3 | 1.685 g/cm^3 solubility in water | | | | | soluble | very soluble surface tension | 0.0728 N/m | | 0.01347 N/m | | | dynamic viscosity | 8.9×10^-4 Pa s (at 25 °C) | | 2.055×10^-5 Pa s (at 25 °C) | 8.9×10^-6 Pa s (at 25 °C) | 0.001 Pa s (at 550 °C) | odor | odorless | | odorless | odorless | | odorless
Units