**Are you an EPFL student looking for a semester project?**

Work with us on data science and visualisation projects, and deploy your project as an app on top of GraphSearch.

Concept# Gibbs free energy

Summary

In thermodynamics, the Gibbs free energy (or Gibbs energy as the recommended name; symbol G) is a thermodynamic potential that can be used to calculate the maximum amount of work, other than pressure-volume work, that may be performed by a thermodynamically closed system at constant temperature and pressure. It also provides a necessary condition for processes such as chemical reactions that may occur under these conditions. The Gibbs free energy is expressed as
: G(p,T) = U + pV - TS = H - TS
where p is pressure, T is the temperature, U is the internal energy, V is volume, H is the enthalpy, and S is the entropy.
The Gibbs free energy change , measured in joules in SI) is the maximum amount of non-volume expansion work that can be extracted from a closed system (one that can exchange heat and work with its surroundings, but not matter) at fixed temperature and pressure. This maximum can be attained only in a completely reversible process. When a syste

Official source

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related publications

Loading

Related people

Loading

Related units

Loading

Related concepts

Loading

Related courses

Loading

Related lectures

Loading

Related people (22)

Related publications (100)

Loading

Loading

Loading

Related units (12)

Related concepts (98)

Entropy

Entropy is a scientific concept, as well as a measurable physical property, that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in

Chemical potential

In thermodynamics, the chemical potential of a species is the energy that can be absorbed or released due to a change of the particle number of the given species, e.g. in a chemical reaction or phase

Enthalpy

Enthalpy ˈɛnθəlpi, a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chem

Related lectures (318)

Related courses (104)

MSE-422: Advanced metallurgy

This course covers the metallurgy, processing and properties of modern high-performance metals and alloys (e.g. advanced steels, Ni-base, Ti-base, High Entropy Alloys etc.). In addition, the principles of computational alloy design as well as approaches for a sustainable metallurgy will be addressed

PHYS-441: Statistical physics of biomacromolecules

Introduction to the application of the notions and methods of theoretical physics to problems in biology.

PHYS-462: Quantum transport in mesoscopic systems

This course will focus on the electron transport in semiconductors, with emphasis on the mesoscopic systems. The aim is to understand the transport of electrons in low dimensional systems, where even particles with statistics different than fermions and bosons will be discussed.

Paulo Henrique Jacob Silva, Ting Mao, Quy Ong Khac, Francesco Stellacci, Xufeng Xu

Dispersion of objects in a fluid phase can be classified as solutions (Gibbs free energy of mixing, Delta G(mix) < 0) or suspensions (Delta G(mix) > 0) depending on their thermodynamic stability. Small objects tend to form solutions, larger ones suspensions, e.g., molecules versus micrometer-sized colloids. Proteins and nanomaterials fall between these two size regimes. The long-standing issue of whether proteins and nanoparticles are dissolved or suspended remains an important research question. Here, a simple, versatile, and experimentally robust method, based on sedimentation equilibrium analytical ultracentrifugation (SE-AUC), which can determine whether proteins, nanoparticles, or polymers form solutions or suspensions, is presented. SE-AUC determines the osmotic pressure profile for a dispersion. Such a profile for solutions (equilibrium one-phase systems) is independent of the initial and the operating conditions. The opposite is true for suspensions that are nonequilibrium two-phase systems. This study proves that bovine serum albumin and lysozyme form solutions while ferritin and apoferritin form suspensions.

This work is devoted to the study of the analyticity properties of thermodynamic potentials (free energy, pressure) for classical lattice systems at low temperature. The central topic of our analysis, in this framework, is to show rigorously the absence of analytic continuation at points of first order phase transition. Our first result applies to the general class of two phase models considered in the Theory of Pirogov-Sinai. The analysis reveals that the Peirls condition, which is the basic hypothesis of the theory, suffices to show the absence of analytic continuation of the pressure at the transition point. In a second part, we study a particular two body potential, of the form γdJ(γx), where γ > 0 is a small parameter and J a function with bounded support (in the limit γ —> 0, this potential gives a rigorous justification of the "equal area rule" of the van der Waals-Maxwell Theory). For all small strictly positive values of the parameter γ, we show that the free energy has no analytic continuation at the transition points. These results confirm early conjectures stating that the finiteness of the range of interaction is responsible for the presence of singularities in the thermodynamic potentials.

Boosted by the technological advances in experimental techniques, cellular biology is nowadays facing the need for quantitative approaches in order to rationalize the huge amount of collected data. A particularly succesfull theoretical framework is provided by Polymer Theory which, combined with molecular simulations, can capture the essential features of biomacromolecules and describe the cellular processes they participate to. This thesis provides a compendium of works showing the strength of this combination. In a first project, we model the twisting properties of amyloid fibrils by means of a simple coarse-grained approach, based on the competition between elasticity and electrostatic repulsion of nearby portions of the fibrils. The model quantitatively recapitulates the evolution of fibril periodicity as a function of the ionic strength of the solution and of the fibril width. A universal mesoscopic structural signature of the fibrils emerges from this picture, predicting a general, parameter-free law for the periodicity of the fibrils which is validated on several experimental results. A second work is focused on the role played by mitochondrial Hsp70 chaperone in the import of cytoplasmic proteins. Particularly, we computed by means of molecular simulations the effective free-energy profile for substrate translocation upon chaperone binding. We then used the resulting free energy to quantitatively characterize the kinetics of the import process and outline the essential role played by Hsp70 in this context. Finally, in a third project we studied the shape properties of a polymer under tension, a physical condition typically realized both in single-molecule experiments and in vivo. By means of analytical calculations and Monte Carlo simulations, we develop a theoretical framework which quantitatively describes these properties, highlighting the interplay between external force and chain size in determining the spatial distribution of a stretched chain.