Graphite is thermodynamically more stable than diamond under standard conditions (ΔG°…
CHEMISTRY · Single correct · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
Graphite is thermodynamically more stable than diamond under standard conditions (ΔG° < 0 for the conversion of diamond to graphite), yet diamonds persist for millions of years. Which option best accounts for this observation?
(a) The forward and reverse rate constants for diamond and graphite are equal, so the system is already at equilibrium and no net conversion occurs.
(b) At the low pressures found at Earth’s surface, Le Châtelier’s principle favors diamond because it occupies less volume than graphite.
(c) The conversion has a large activation energy, so the rate of the thermodynamically favored process is negligibly small at Earth-surface temperatures.
(d) Because the process is endothermic, a negative value of ΔG∘ does not indicate that the conversion is thermodynamically favorable.