The conversion of graphite has only a small positive value of ΔH.

C (graphite) → C (diamond) ΔH = +2.1 kJ mol⁻¹

However, the production of synthetic diamonds using this reaction is very difficult. Which statements help to explain this?

1. The activation energy of the reaction is large.
2. An equilibrium exists between diamond and graphite.
3. Only exothermic reactions can be made to occur readily.

To explain why the conversion of graphite to diamond is difficult despite a small positive change in enthalpy ( Δ H = + 2.1 kJ mol − 1 ) , we need to consider a few key concepts related to thermodynamics and reaction kinetics.

Activation Energy:

The activation energy is the minimum energy required to start a chemical reaction. In this case, converting graphite to diamond involves breaking and rearranging the bonds between carbon atoms. This process requires a substantial amount of energy because the carbon atoms in graphite are arranged in a stable hexagonal structure.
The statement "The activation energy of the reaction is large" is crucial. A high activation energy means that the reaction is slow at standard conditions, thus making the process of converting graphite to diamond difficult without significant external energy.


Equilibrium Considerations:

Although there is a theoretical equilibrium where diamond and graphite can interconvert, under standard conditions, graphite is more stable and favored due to its lower energy state.
The statement "An equilibrium exists between diamond and graphite" implies that both can interconvert, but practical conversion would greatly favor graphite, further complicating the formation of diamond.


Nature of Exothermic and Endothermic Reactions:

The statement "Only exothermic reactions can be made to occur readily" is not accurate. While exothermic reactions tend to occur more spontaneously because they release energy, endothermic reactions can also proceed with the right conditions, particularly if the activation energy barrier can be overcome.
The conversion of graphite to diamond is an endothermic process 0)"> ( Δ H > 0 ) , meaning it requires an input of energy to proceed, which aligns with the need for high pressures and temperatures to synthesize diamonds artificially.



In summary, the difficulty in synthesizing diamonds from graphite primarily lies in the high activation energy required for carbon atoms to re-arrange into the diamond structure and the relative stability of graphite under normal conditions."}

Answered by OliviaMariThompson | 2025-07-21

The difficulty in converting graphite to diamond, despite a small positive enthalpy change, is largely due to the high activation energy required for the reaction and the stability of graphite at standard conditions. An equilibrium exists favoring graphite, making diamond synthesis challenging, while both endothermic and exothermic reactions can occur under the right conditions. Overall, significant energy input is necessary to facilitate this transformation.
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Answered by OliviaMariThompson | 2025-07-26