Naslov
The Gibbs function of a chemical reaction

Autori
Cvitaš, Tomislav

Izvornik
Croatica chemica acta (0011-1643) 80 (2007), 3/4; 605-612

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
extent of reaction; Gibbs function; reaction quantities; chemical equilibrium; degree of reaction

Sažetak
By defining the extent of reaction as the amount of chemical reactions (moles of reactions) as given by the reaction equation the stoichiometric number of a species taking part in the reaction can be defined as the change in the amount of the species with the extent of reaction. The change in the Gibbs function with the advancement is analyzed in detail for a system of reacting ideal gases at constant temperature and pressure. The changes are split into three contributions: the standard Gibbs function of the reaction, the pressure correction for cases when the total pressure differs from the standard value and the contribution of mixing. The first two contributions depend linearly on the extent of reaction and the third is the only one causing the Gibbs function to have a minimum between the minimum and maximum extent, or at a degree of reaction between 0 and 1. The most convenient way to describe such processes is by plotting the change in the Gibbs function divided by the maximum extent of reaction as a function of the degree of reaction, where both axes represent intensive quantities. Such a plot does not depend on the size of the system, but only on the temperature, pressure, ratio of initial amounts and the nature of the reaction. A spread-sheet program (MS Excel) depicting the variation of the Gibbs function with the degree of reaction for given input data is provided separately as supplementary material available via the Internet.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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