Chemistry - Thermochemistry Question with Solution | TestHub

Question Explanation:

Determine the expression for the resonance energy of benzene using hydrogenation enthalpies. Concept:

Resonance Energy.

Solution:

Resonance energy is the difference between the theoretical enthalpy change (for a hypothetical Kekulé structure with three isolated double bonds) and the actual (experimental) enthalpy change. Calculation:

$3{\mathrm{C}}_2{\mathrm{H}}_2\to {\mathrm{C}}_6{\mathrm{H}}_6+\Delta \mathrm{H}$ resonance

$\Delta \mathrm{H}$ resonance $+{\mathrm{x}}_2=3{\mathrm{x}}_1$

$$\Delta \text{ H resonance }=3x_1-x_2$$

Final Answer: $3{\mathrm{x}}_1-{\mathrm{x}}_2$