Final answer:
The question involves estimating the enthalpy change (ΔH) for the formation of ammonia from nitrogen and hydrogen gases using bond energies. The process involves calculating the energy needed to break bonds in reactants and the energy released in forming bonds in products, and then subtracting the former from the latter.
Step-by-step explanation:
The student is asking for an estimation of the enthalpy change (ΔH) for the reaction where nitrogen (N₂) gas reacts with hydrogen (H₂) gas to form ammonia (NH₃). To estimate this, bond energies are used to calculate the total energy required to break the bonds of the reactants and the energy released when the products are formed.
To obtain an accurate estimation, the student will have to sum up the bond energies of all the bonds broken in the reactants and then subtract the sum of the bond energies of all the bonds formed in the products. Here's a more detailed breakdown:
- Step 1: Calculate the total energy needed to break all the bonds in the reactants. In this case, it's the energy to break the triple bond of N₂ and the single bonds in 3 H₂ molecules.
- Step 2: Do the same for the products, which involves calculating the energy released from forming six N-H bonds in 2 NH₃ molecules.
- Step 3: Identify the bond dissociation energies of these bonds, usually found in a table in the chemistry textbook or provided data.
- Step 4: Set up the calculation by subtracting the energy of bond formation from the energy of bond dissociation to get the approximate ΔH for the reaction.
Given the specified ΔH of -92.2 kJ/mol for the reaction, this estimation can be compared to the literature value, knowing that the actual enthalpy change can differ due to experimental conditions and the theoretical approach used.