N2H4 = NH3 + N2

NH_2NH_2 diazane ⟶ NH_3 ammonia + N_2 nitrogen

Balance the chemical equation algebraically: NH_2NH_2 ⟶ NH_3 + N_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 NH_2NH_2 ⟶ c_2 NH_3 + c_3 N_2 Set the number of atoms in the reactants equal to the number of atoms in the products for H and N: H: | 4 c_1 = 3 c_2 N: | 2 c_1 = 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_3 = 1 and solve the system of equations for the remaining coefficients: c_1 = 3 c_2 = 4 c_3 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 NH_2NH_2 ⟶ 4 NH_3 + N_2

⟶ +

diazane ⟶ ammonia + nitrogen

| diazane | ammonia | nitrogen molecular enthalpy | 50.6 kJ/mol | -45.9 kJ/mol | 0 kJ/mol total enthalpy | 151.8 kJ/mol | -183.6 kJ/mol | 0 kJ/mol | H_initial = 151.8 kJ/mol | H_final = -183.6 kJ/mol | ΔH_rxn^0 | -183.6 kJ/mol - 151.8 kJ/mol = -335.4 kJ/mol (exothermic) | |

| diazane | ammonia | nitrogen molecular free energy | 149.3 kJ/mol | -16.4 kJ/mol | 0 kJ/mol total free energy | 447.9 kJ/mol | -65.6 kJ/mol | 0 kJ/mol | G_initial = 447.9 kJ/mol | G_final = -65.6 kJ/mol | ΔG_rxn^0 | -65.6 kJ/mol - 447.9 kJ/mol = -513.5 kJ/mol (exergonic) | |

| diazane | ammonia | nitrogen molecular entropy | 121 J/(mol K) | 193 J/(mol K) | 192 J/(mol K) total entropy | 363 J/(mol K) | 772 J/(mol K) | 192 J/(mol K) | S_initial = 363 J/(mol K) | S_final = 964 J/(mol K) | ΔS_rxn^0 | 964 J/(mol K) - 363 J/(mol K) = 601 J/(mol K) (endoentropic) | |

Construct the equilibrium constant, K, expression for: NH_2NH_2 ⟶ NH_3 + N_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: 3 NH_2NH_2 ⟶ 4 NH_3 + N_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 NH_2NH_2 | 3 | -3 NH_3 | 4 | 4 N_2 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression NH_2NH_2 | 3 | -3 | ([NH2NH2])^(-3) NH_3 | 4 | 4 | ([NH3])^4 N_2 | 1 | 1 | [N2] 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 = ([NH2NH2])^(-3) ([NH3])^4 [N2] = (([NH3])^4 [N2])/([NH2NH2])^3

Construct the rate of reaction expression for: NH_2NH_2 ⟶ NH_3 + N_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: 3 NH_2NH_2 ⟶ 4 NH_3 + N_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 NH_2NH_2 | 3 | -3 NH_3 | 4 | 4 N_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 NH_2NH_2 | 3 | -3 | -1/3 (Δ[NH2NH2])/(Δt) NH_3 | 4 | 4 | 1/4 (Δ[NH3])/(Δt) N_2 | 1 | 1 | (Δ[N2])/(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 = -1/3 (Δ[NH2NH2])/(Δt) = 1/4 (Δ[NH3])/(Δt) = (Δ[N2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| diazane | ammonia | nitrogen formula | NH_2NH_2 | NH_3 | N_2 Hill formula | H_4N_2 | H_3N | N_2 name | diazane | ammonia | nitrogen IUPAC name | hydrazine | ammonia | molecular nitrogen

| diazane | ammonia | nitrogen molar mass | 32.046 g/mol | 17.031 g/mol | 28.014 g/mol phase | liquid (at STP) | gas (at STP) | gas (at STP) melting point | 1 °C | -77.73 °C | -210 °C boiling point | 113.5 °C | -33.33 °C | -195.79 °C density | 1.011 g/cm^3 | 6.96×10^-4 g/cm^3 (at 25 °C) | 0.001251 g/cm^3 (at 0 °C) solubility in water | miscible | | insoluble surface tension | 0.0667 N/m | 0.0234 N/m | 0.0066 N/m dynamic viscosity | 8.76×10^-4 Pa s (at 25 °C) | 1.009×10^-5 Pa s (at 25 °C) | 1.78×10^-5 Pa s (at 25 °C) odor | | | odorless