Question

Based on the thermochemical equation, which other equation shows the correct relationship between the chemical species and the enthalpy change?

[3H₂ + N₂ → 2NH₃, quad Δ H = -96 ,kJ]

a) (3/2H₂ + 1/2N₂ → NH₃, quad Δ H = -96 ,kJ)

b) (3/2H₂ + 1/2N₂ → NH₃, quad Δ H = +48 ,kJ)

c) (3H₂ + N₂ → 2NH₃, quad Δ H = +96 ,kJ)

d) (NH₃ → 3/2H₂ + 1/2N₂, quad Δ H = +48 ,kJ)

Answer 1

The equation that shows the correct relationship between the chemical species and the enthalpy change is (3/2H₂ + 1/2N₂ → NH₃, ΔH = -48 kJ), where the stoichiometry and enthalpy are proportionally scaled down.

Step-by-step explanation:

The correct relationship between the chemical species and the enthalpy change for the reaction 3H₂ + N₂ → 2NH₃, ΔH = -92 kJ is such that when the balanced equation is divided by two to yield half the amount of products, the enthalpy change should also be halved and should remain exothermic, as enthalpy is an extensive property.

This corresponds to equation b: (3/2H₂ + 1/2N₂ → NH₃, ΔH = -48 kJ), which correctly represents the stoichiometry and enthalpy change for half the reaction. This ensures the enthalpy change is proportional to the moles of substances involved in the reaction.