What is the difference between [math]\Delta G[/math] and [math]\Delta G°[/math] in thermodynamics?


Відповідь 1:

ΔG0describestheamountofGibbsfreeenergythatthesystemhasunderstandardconditions.[math]ΔG[/math]ismoregeneral,theGibbsfreeenergyatanytemperature.Itconsistsofthe[math]ΔG0[/math]plusanotherfactorproportionaltothelogofthepressurecomparedwiththepressureunderstandardconditions.\Delta G^0 describes the amount of Gibbs free energy that the system has under standard conditions. [math]\Delta G[/math] is more general, the Gibbs free energy at any temperature. It consists of the [math]\Delta G^0[/math] plus another factor proportional to the log of the pressure compared with the pressure under standard conditions.

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Thatis,whenthepressuregoesup,theincreaseinGisproportionaltothelogofthepressure,ascomparedwiththestandardpressure.Whenthepressureisthesameasstandardpressure,ΔG0=ΔGbecause[math]logpp0=log1=0[/math].That is, when the pressure goes up, the increase in G is proportional to the log of the pressure, as compared with the standard pressure. When the pressure is the same as standard pressure, \Delta G^0 = \Delta G because [math]\log \frac{p}{p^0}=\log 1 = 0[/math].