HNO2 + K2SiO3 = KNO2 + H2SiO3

HNO_2 nitrous acid + K2SiO3 ⟶ KNO_2 potassium nitrite + H_2O_3Si metasilicic acid

Balance the chemical equation algebraically: HNO_2 + K2SiO3 ⟶ KNO_2 + H_2O_3Si Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HNO_2 + c_2 K2SiO3 ⟶ c_3 KNO_2 + c_4 H_2O_3Si Set the number of atoms in the reactants equal to the number of atoms in the products for H, N, O, K and Si: H: | c_1 = 2 c_4 N: | c_1 = c_3 O: | 2 c_1 + 3 c_2 = 2 c_3 + 3 c_4 K: | 2 c_2 = c_3 Si: | c_2 = 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 = 2 c_2 = 1 c_3 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 HNO_2 + K2SiO3 ⟶ 2 KNO_2 + H_2O_3Si

+ K2SiO3 ⟶ +

nitrous acid + K2SiO3 ⟶ potassium nitrite + metasilicic acid

Construct the equilibrium constant, K, expression for: HNO_2 + K2SiO3 ⟶ KNO_2 + H_2O_3Si 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: 2 HNO_2 + K2SiO3 ⟶ 2 KNO_2 + H_2O_3Si 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 HNO_2 | 2 | -2 K2SiO3 | 1 | -1 KNO_2 | 2 | 2 H_2O_3Si | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HNO_2 | 2 | -2 | ([HNO2])^(-2) K2SiO3 | 1 | -1 | ([K2SiO3])^(-1) KNO_2 | 2 | 2 | ([KNO2])^2 H_2O_3Si | 1 | 1 | [H2O3Si] 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 = ([HNO2])^(-2) ([K2SiO3])^(-1) ([KNO2])^2 [H2O3Si] = (([KNO2])^2 [H2O3Si])/(([HNO2])^2 [K2SiO3])

Construct the rate of reaction expression for: HNO_2 + K2SiO3 ⟶ KNO_2 + H_2O_3Si 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: 2 HNO_2 + K2SiO3 ⟶ 2 KNO_2 + H_2O_3Si 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 HNO_2 | 2 | -2 K2SiO3 | 1 | -1 KNO_2 | 2 | 2 H_2O_3Si | 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 HNO_2 | 2 | -2 | -1/2 (Δ[HNO2])/(Δt) K2SiO3 | 1 | -1 | -(Δ[K2SiO3])/(Δt) KNO_2 | 2 | 2 | 1/2 (Δ[KNO2])/(Δt) H_2O_3Si | 1 | 1 | (Δ[H2O3Si])/(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 = -1/2 (Δ[HNO2])/(Δt) = -(Δ[K2SiO3])/(Δt) = 1/2 (Δ[KNO2])/(Δt) = (Δ[H2O3Si])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| nitrous acid | K2SiO3 | potassium nitrite | metasilicic acid formula | HNO_2 | K2SiO3 | KNO_2 | H_2O_3Si Hill formula | HNO_2 | K2O3Si | KNO_2 | H_2O_3Si name | nitrous acid | | potassium nitrite | metasilicic acid IUPAC name | nitrous acid | | potassium nitrite | dihydroxy-oxo-silane

| nitrous acid | K2SiO3 | potassium nitrite | metasilicic acid molar mass | 47.013 g/mol | 154.28 g/mol | 85.103 g/mol | 78.098 g/mol phase | | | solid (at STP) | solid (at STP) melting point | | | 350 °C | 1704 °C density | | | 1.915 g/cm^3 | 1 g/cm^3