NaNO3 = O2 + NaNO2

NaNO_3 (sodium nitrate) ⟶ O_2 (oxygen) + NaNO_2 (sodium nitrite)

Balance the chemical equation algebraically: NaNO_3 ⟶ O_2 + NaNO_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 NaNO_3 ⟶ c_2 O_2 + c_3 NaNO_2 Set the number of atoms in the reactants equal to the number of atoms in the products for N, Na and O: N: | c_1 = c_3 Na: | c_1 = c_3 O: | 3 c_1 = 2 c_2 + 2 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 1 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 NaNO_3 ⟶ O_2 + 2 NaNO_2

⟶ +

sodium nitrate ⟶ oxygen + sodium nitrite

| sodium nitrate | oxygen | sodium nitrite molecular enthalpy | -467.9 kJ/mol | 0 kJ/mol | -359 kJ/mol total enthalpy | -935.8 kJ/mol | 0 kJ/mol | -718 kJ/mol | H_initial = -935.8 kJ/mol | H_final = -718 kJ/mol | ΔH_rxn^0 | -718 kJ/mol - -935.8 kJ/mol = 217.8 kJ/mol (endothermic) | |

| sodium nitrate | oxygen | sodium nitrite molecular free energy | -366 kJ/mol | 231.7 kJ/mol | -284.6 kJ/mol total free energy | -732 kJ/mol | 231.7 kJ/mol | -569.2 kJ/mol | G_initial = -732 kJ/mol | G_final = -337.5 kJ/mol | ΔG_rxn^0 | -337.5 kJ/mol - -732 kJ/mol = 394.5 kJ/mol (endergonic) | |

Construct the equilibrium constant, K, expression for: NaNO_3 ⟶ O_2 + NaNO_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: 2 NaNO_3 ⟶ O_2 + 2 NaNO_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 NaNO_3 | 2 | -2 O_2 | 1 | 1 NaNO_2 | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression NaNO_3 | 2 | -2 | ([NaNO3])^(-2) O_2 | 1 | 1 | [O2] NaNO_2 | 2 | 2 | ([NaNO2])^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 = ([NaNO3])^(-2) [O2] ([NaNO2])^2 = ([O2] ([NaNO2])^2)/([NaNO3])^2

Construct the rate of reaction expression for: NaNO_3 ⟶ O_2 + NaNO_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: 2 NaNO_3 ⟶ O_2 + 2 NaNO_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 NaNO_3 | 2 | -2 O_2 | 1 | 1 NaNO_2 | 2 | 2 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 NaNO_3 | 2 | -2 | -1/2 (Δ[NaNO3])/(Δt) O_2 | 1 | 1 | (Δ[O2])/(Δt) NaNO_2 | 2 | 2 | 1/2 (Δ[NaNO2])/(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[NaNO3])/(Δt) = (Δ[O2])/(Δt) = 1/2 (Δ[NaNO2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| sodium nitrate | oxygen | sodium nitrite formula | NaNO_3 | O_2 | NaNO_2 Hill formula | NNaO_3 | O_2 | NNaO_2 name | sodium nitrate | oxygen | sodium nitrite IUPAC name | sodium nitrate | molecular oxygen | sodium nitrite

| sodium nitrate | oxygen | sodium nitrite molar mass | 84.994 g/mol | 31.998 g/mol | 68.995 g/mol phase | solid (at STP) | gas (at STP) | solid (at STP) melting point | 306 °C | -218 °C | 271 °C boiling point | | -183 °C | density | 2.26 g/cm^3 | 0.001429 g/cm^3 (at 0 °C) | 2.168 g/cm^3 solubility in water | soluble | | surface tension | | 0.01347 N/m | dynamic viscosity | 0.003 Pa s (at 250 °C) | 2.055×10^-5 Pa s (at 25 °C) | odor | | odorless |