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H2O + I2 + H3PO2 = HI + H3PO3

Input interpretation

H_2O water + I_2 iodine + H3PO2 ⟶ HI hydrogen iodide + HP(O)(OH)_2 phosphorous acid
H_2O water + I_2 iodine + H3PO2 ⟶ HI hydrogen iodide + HP(O)(OH)_2 phosphorous acid

Balanced equation

Balance the chemical equation algebraically: H_2O + I_2 + H3PO2 ⟶ HI + HP(O)(OH)_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O + c_2 I_2 + c_3 H3PO2 ⟶ c_4 HI + c_5 HP(O)(OH)_2 Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, I and P: H: | 2 c_1 + 3 c_3 = c_4 + 3 c_5 O: | c_1 + 2 c_3 = 3 c_5 I: | 2 c_2 = c_4 P: | c_3 = c_5 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 = 2 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: |   | H_2O + I_2 + H3PO2 ⟶ 2 HI + HP(O)(OH)_2
Balance the chemical equation algebraically: H_2O + I_2 + H3PO2 ⟶ HI + HP(O)(OH)_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O + c_2 I_2 + c_3 H3PO2 ⟶ c_4 HI + c_5 HP(O)(OH)_2 Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, I and P: H: | 2 c_1 + 3 c_3 = c_4 + 3 c_5 O: | c_1 + 2 c_3 = 3 c_5 I: | 2 c_2 = c_4 P: | c_3 = c_5 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 = 2 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | H_2O + I_2 + H3PO2 ⟶ 2 HI + HP(O)(OH)_2

Structures

 + + H3PO2 ⟶ +
+ + H3PO2 ⟶ +

Names

water + iodine + H3PO2 ⟶ hydrogen iodide + phosphorous acid
water + iodine + H3PO2 ⟶ hydrogen iodide + phosphorous acid

Equilibrium constant

Construct the equilibrium constant, K, expression for: H_2O + I_2 + H3PO2 ⟶ HI + HP(O)(OH)_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: H_2O + I_2 + H3PO2 ⟶ 2 HI + HP(O)(OH)_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 H_2O | 1 | -1 I_2 | 1 | -1 H3PO2 | 1 | -1 HI | 2 | 2 HP(O)(OH)_2 | 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 | 1 | -1 | ([H2O])^(-1) I_2 | 1 | -1 | ([I2])^(-1) H3PO2 | 1 | -1 | ([H3PO2])^(-1) HI | 2 | 2 | ([HI])^2 HP(O)(OH)_2 | 1 | 1 | [HP(O)(OH)2] 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])^(-1) ([I2])^(-1) ([H3PO2])^(-1) ([HI])^2 [HP(O)(OH)2] = (([HI])^2 [HP(O)(OH)2])/([H2O] [I2] [H3PO2])
Construct the equilibrium constant, K, expression for: H_2O + I_2 + H3PO2 ⟶ HI + HP(O)(OH)_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: H_2O + I_2 + H3PO2 ⟶ 2 HI + HP(O)(OH)_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 H_2O | 1 | -1 I_2 | 1 | -1 H3PO2 | 1 | -1 HI | 2 | 2 HP(O)(OH)_2 | 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 | 1 | -1 | ([H2O])^(-1) I_2 | 1 | -1 | ([I2])^(-1) H3PO2 | 1 | -1 | ([H3PO2])^(-1) HI | 2 | 2 | ([HI])^2 HP(O)(OH)_2 | 1 | 1 | [HP(O)(OH)2] 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])^(-1) ([I2])^(-1) ([H3PO2])^(-1) ([HI])^2 [HP(O)(OH)2] = (([HI])^2 [HP(O)(OH)2])/([H2O] [I2] [H3PO2])

Rate of reaction

Construct the rate of reaction expression for: H_2O + I_2 + H3PO2 ⟶ HI + HP(O)(OH)_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: H_2O + I_2 + H3PO2 ⟶ 2 HI + HP(O)(OH)_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 H_2O | 1 | -1 I_2 | 1 | -1 H3PO2 | 1 | -1 HI | 2 | 2 HP(O)(OH)_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 H_2O | 1 | -1 | -(Δ[H2O])/(Δt) I_2 | 1 | -1 | -(Δ[I2])/(Δt) H3PO2 | 1 | -1 | -(Δ[H3PO2])/(Δt) HI | 2 | 2 | 1/2 (Δ[HI])/(Δt) HP(O)(OH)_2 | 1 | 1 | (Δ[HP(O)(OH)2])/(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[H2O])/(Δt) = -(Δ[I2])/(Δt) = -(Δ[H3PO2])/(Δt) = 1/2 (Δ[HI])/(Δt) = (Δ[HP(O)(OH)2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)
Construct the rate of reaction expression for: H_2O + I_2 + H3PO2 ⟶ HI + HP(O)(OH)_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: H_2O + I_2 + H3PO2 ⟶ 2 HI + HP(O)(OH)_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 H_2O | 1 | -1 I_2 | 1 | -1 H3PO2 | 1 | -1 HI | 2 | 2 HP(O)(OH)_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 H_2O | 1 | -1 | -(Δ[H2O])/(Δt) I_2 | 1 | -1 | -(Δ[I2])/(Δt) H3PO2 | 1 | -1 | -(Δ[H3PO2])/(Δt) HI | 2 | 2 | 1/2 (Δ[HI])/(Δt) HP(O)(OH)_2 | 1 | 1 | (Δ[HP(O)(OH)2])/(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[H2O])/(Δt) = -(Δ[I2])/(Δt) = -(Δ[H3PO2])/(Δt) = 1/2 (Δ[HI])/(Δt) = (Δ[HP(O)(OH)2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

Chemical names and formulas

 | water | iodine | H3PO2 | hydrogen iodide | phosphorous acid formula | H_2O | I_2 | H3PO2 | HI | HP(O)(OH)_2 Hill formula | H_2O | I_2 | H3O2P | HI | H_3O_3P name | water | iodine | | hydrogen iodide | phosphorous acid IUPAC name | water | molecular iodine | | hydrogen iodide | phosphorous acid
| water | iodine | H3PO2 | hydrogen iodide | phosphorous acid formula | H_2O | I_2 | H3PO2 | HI | HP(O)(OH)_2 Hill formula | H_2O | I_2 | H3O2P | HI | H_3O_3P name | water | iodine | | hydrogen iodide | phosphorous acid IUPAC name | water | molecular iodine | | hydrogen iodide | phosphorous acid

Substance properties

 | water | iodine | H3PO2 | hydrogen iodide | phosphorous acid molar mass | 18.015 g/mol | 253.80894 g/mol | 65.996 g/mol | 127.912 g/mol | 81.995 g/mol phase | liquid (at STP) | solid (at STP) | | gas (at STP) | solid (at STP) melting point | 0 °C | 113 °C | | -50.76 °C | 74 °C boiling point | 99.9839 °C | 184 °C | | -35.55 °C |  density | 1 g/cm^3 | 4.94 g/cm^3 | | 0.005228 g/cm^3 (at 25 °C) | 1.597 g/cm^3 solubility in water | | | | very soluble |  surface tension | 0.0728 N/m | | | |  dynamic viscosity | 8.9×10^-4 Pa s (at 25 °C) | 0.00227 Pa s (at 116 °C) | | 0.001321 Pa s (at -39 °C) |  odor | odorless | | | |
| water | iodine | H3PO2 | hydrogen iodide | phosphorous acid molar mass | 18.015 g/mol | 253.80894 g/mol | 65.996 g/mol | 127.912 g/mol | 81.995 g/mol phase | liquid (at STP) | solid (at STP) | | gas (at STP) | solid (at STP) melting point | 0 °C | 113 °C | | -50.76 °C | 74 °C boiling point | 99.9839 °C | 184 °C | | -35.55 °C | density | 1 g/cm^3 | 4.94 g/cm^3 | | 0.005228 g/cm^3 (at 25 °C) | 1.597 g/cm^3 solubility in water | | | | very soluble | surface tension | 0.0728 N/m | | | | dynamic viscosity | 8.9×10^-4 Pa s (at 25 °C) | 0.00227 Pa s (at 116 °C) | | 0.001321 Pa s (at -39 °C) | odor | odorless | | | |

Units