Fe + N2 = Fe2N

Fe iron + N_2 nitrogen ⟶ Fe2N

Balance the chemical equation algebraically: Fe + N_2 ⟶ Fe2N Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Fe + c_2 N_2 ⟶ c_3 Fe2N Set the number of atoms in the reactants equal to the number of atoms in the products for Fe and N: Fe: | c_1 = 2 c_3 N: | 2 c_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 = 4 c_2 = 1 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 4 Fe + N_2 ⟶ 2 Fe2N

+ ⟶ Fe2N

iron + nitrogen ⟶ Fe2N

Construct the equilibrium constant, K, expression for: Fe + N_2 ⟶ Fe2N 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: 4 Fe + N_2 ⟶ 2 Fe2N 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 Fe | 4 | -4 N_2 | 1 | -1 Fe2N | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Fe | 4 | -4 | ([Fe])^(-4) N_2 | 1 | -1 | ([N2])^(-1) Fe2N | 2 | 2 | ([Fe2N])^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 = ([Fe])^(-4) ([N2])^(-1) ([Fe2N])^2 = ([Fe2N])^2/(([Fe])^4 [N2])

Construct the rate of reaction expression for: Fe + N_2 ⟶ Fe2N 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: 4 Fe + N_2 ⟶ 2 Fe2N 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 Fe | 4 | -4 N_2 | 1 | -1 Fe2N | 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 Fe | 4 | -4 | -1/4 (Δ[Fe])/(Δt) N_2 | 1 | -1 | -(Δ[N2])/(Δt) Fe2N | 2 | 2 | 1/2 (Δ[Fe2N])/(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 = -1/4 (Δ[Fe])/(Δt) = -(Δ[N2])/(Δt) = 1/2 (Δ[Fe2N])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| iron | nitrogen | Fe2N formula | Fe | N_2 | Fe2N name | iron | nitrogen | IUPAC name | iron | molecular nitrogen |

| iron | nitrogen | Fe2N molar mass | 55.845 g/mol | 28.014 g/mol | 125.7 g/mol phase | solid (at STP) | gas (at STP) | melting point | 1535 °C | -210 °C | boiling point | 2750 °C | -195.79 °C | density | 7.874 g/cm^3 | 0.001251 g/cm^3 (at 0 °C) | solubility in water | insoluble | insoluble | surface tension | | 0.0066 N/m | dynamic viscosity | | 1.78×10^-5 Pa s (at 25 °C) | odor | | odorless |