This long titled paper is interesting. The authors assert that chemical thermal dynamic analysis can be used to determine whether a reaction will or will not occur, at a specific temperature and pressure. They assert that using chemical thermal dynamic analysis, that it can be shown that long chain carbon molecules will not spontaneously be formed, except at great pressures (at depths greater than 100 km). Then they preform an experiment that produces long chain hydrocarbons using a diamond anvil that can recreate the pressure at great depths.
The following are excerpts from this paper.
The evolution of multi-component systems at high pressures: VI. The thermodynamic stability of the hydrogen–carbon system: The genesis of hydrocarbons and the origin of petroleum, By Kenney, Kutcherov, Bendeliani, and Alekseev
http://www.pnas.org/cgi/reprint/99/17/10976
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Natural petroleum is a hydrogen–carbon (H–C) system, in distinctly nonequilibrium states, composed of mixtures of highly reduced hydrocarbon molecules, all of very high chemical potential and most in the liquid phase. As such, the phenomenon of the terrestrial existence of natural petroleum in the near-surface crust of the Earth has presented several challenges, most of which have remained unresolved until recently. The primary scientific problem of petroleum has been the existence and genesis of the individual hydrocarbon molecules themselves: how, and under what thermodynamic conditions, can such highly reduced molecules of high chemical potential evolve?
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The theoretical analyses establish that the normal alkanes, the homologous hydrocarbon group of lowest chemical potential, evolve only at pressures greater than approx. 30 kbar, excepting only the lightest, methane. The pressure of 30 kbar corresponds to depths of approx.100 km. For experimental verification of the predictions of the theoretical analysis, a special high-pressure apparatus has been designed that permits investigations at pressures to 50 kbar and temperatures to 1,500°C and also allows rapid cooling while maintaining high pressures. The high-pressure genesis of petroleum hydrocarbons has been demonstrated using only the reagents solid iron oxide, FeO, and marble, CaCO3, 99.9% pure and wet with triple distilled water.
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The expression in the second line of Eq. 2 states further that for any circumstance for which the Affinity does not vanish, there exists a generalized thermodynamic force that drives the system toward equilibrium. The constraints of this expression assure that an apple, having disconnected from its bough, does not fall, say, half way to the ground and there stop (a phenomenon not prohibited by the first law) but must continue to fall until the ground. These constraints force a chemically reactive system to evolve always toward the state of lowest thermodynamic Affinity.
These constraints force a chemically reactive system to evolve always toward the state of lowest thermodynamic Affinity. Thus, the evolution of a chemically reactive, multicomponent system may be determined at any temperature, pressure, or composition whenever the chemical potentials of its components are known. To ascertain the thermodynamic regime of the spontaneous evolution of hydrocarbons, their chemical potentials must be determined.
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