Final answer:
The spontaneity of the reaction from acetylene to benzene depends on the Gibbs free energy change, which requires knowledge of the enthalpy and entropy changes.
Step-by-step explanation:
To determine if the reaction of acetylene to benzene (3C₂H₂(g) ⇒ C6H6(g)) is spontaneous at a certain temperature, we can use the Gibbs free energy change (ΔG) equation: ΔG = ΔH - TΔS. A negative ΔG indicates a spontaneous process.
However, without specific values of enthalpy (ΔH) and entropy (ΔS) change at the temperatures in question (25 °C and 850 °C), we cannot calculate the exact ΔG to determine spontaneity. Generally, if the equilibrium constant (Ke) is significantly larger than 1, the reaction is more likely to be spontaneous at that temperature.
Commercially, a higher equilibrium constant (Ke) would be more desirable for this reaction. A Ke of approximately 10 would indicate that benzene is favored, making the process more efficient for industrial purposes.
Even if the reaction were thermodynamically favorable (spontaneous) under certain conditions, not all acetylene is found as benzene due to kinetic limitations or a mixture of different conditions in which acetylene exists where the transformation to benzene is not spontaneous.
Additionally, hybridization of carbon atoms varies between acetylene (sp hybridization) and benzene (sp² hybridization), affecting the stability and reactivity of the molecules.