LiH = H2 + Li

LiH lithium hydride ⟶ H_2 hydrogen + Li lithium

Balance the chemical equation algebraically: LiH ⟶ H_2 + Li Add stoichiometric coefficients, c_i, to the reactants and products: c_1 LiH ⟶ c_2 H_2 + c_3 Li Set the number of atoms in the reactants equal to the number of atoms in the products for H and Li: H: | c_1 = 2 c_2 Li: | c_1 = 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 LiH ⟶ H_2 + 2 Li

⟶ +

lithium hydride ⟶ hydrogen + lithium

| lithium hydride | hydrogen | lithium molecular enthalpy | -90.5 kJ/mol | 0 kJ/mol | 0 kJ/mol total enthalpy | -181 kJ/mol | 0 kJ/mol | 0 kJ/mol | H_initial = -181 kJ/mol | H_final = 0 kJ/mol | ΔH_rxn^0 | 0 kJ/mol - -181 kJ/mol = 181 kJ/mol (endothermic) | |

Construct the equilibrium constant, K, expression for: LiH ⟶ H_2 + Li 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 LiH ⟶ H_2 + 2 Li 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 LiH | 2 | -2 H_2 | 1 | 1 Li | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression LiH | 2 | -2 | ([LiH])^(-2) H_2 | 1 | 1 | [H2] Li | 2 | 2 | ([Li])^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 = ([LiH])^(-2) [H2] ([Li])^2 = ([H2] ([Li])^2)/([LiH])^2

Construct the rate of reaction expression for: LiH ⟶ H_2 + Li 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 LiH ⟶ H_2 + 2 Li 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 LiH | 2 | -2 H_2 | 1 | 1 Li | 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 LiH | 2 | -2 | -1/2 (Δ[LiH])/(Δt) H_2 | 1 | 1 | (Δ[H2])/(Δt) Li | 2 | 2 | 1/2 (Δ[Li])/(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[LiH])/(Δt) = (Δ[H2])/(Δt) = 1/2 (Δ[Li])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| lithium hydride | hydrogen | lithium formula | LiH | H_2 | Li Hill formula | HLi | H_2 | Li name | lithium hydride | hydrogen | lithium IUPAC name | lithium hydride | molecular hydrogen | lithium

| lithium hydride | hydrogen | lithium molar mass | 7.95 g/mol | 2.016 g/mol | 6.94 g/mol phase | solid (at STP) | gas (at STP) | solid (at STP) melting point | 680 °C | -259.2 °C | 180 °C boiling point | | -252.8 °C | 1342 °C density | 0.82 g/cm^3 | 8.99×10^-5 g/cm^3 (at 0 °C) | 0.534 g/cm^3 solubility in water | reacts | | decomposes surface tension | | | 0.3975 N/m dynamic viscosity | | 8.9×10^-6 Pa s (at 25 °C) | odor | | odorless |