The stability of phases can be predicted by the chemical potential, in that the most stable form of the substance will have the minimum chemical potential at the given temperature and pressure. Carbon dioxide phase diagram. ... Chemical Potential and Gibbs Free Energy - … We then discuss the role of the chemical potential in understanding phase transitions with a focus on the van der Waals equation of state. Now follow the diagram from the solid phase into the liquid phase region. Together they represent the same system as Fig. This includes vapor-liquid equilibrium, solid-liquid equilibrium, and liquid-liquid equilibrium. The chemical potential of salt solutions is the basis for phase equilibrium calculations for solutions with salts. As the temperature drops the chemical potentials of solid phase Boverlap with that of the liquid phase. Finding stable states from the chemical potential of a compound. If the substance doesn't melt at T f , it's chemical potential would follow the light colored line. The Chemical Potential and Phase Equilibria c 2009 by Harvey Gould and Jan Tobochnik 6 July 2009 We discuss the nature of the chemical potential by considering some simple models and simulations.
1. If a potential axis is replaced with the corresponding mole fraction, the two-phase line in the potential diagram opens up into a two-phase field. The shape of the phase diagram is determined by the molar entropy of molar volume of each of the phases in the diagram. The two phase diagrams look exactly alike because they have been constructed for a symmetric system. The resulting phase diagram is automatically plotted by the Figure module. 5. Chemical system classifications are designed generally to name the simplest possible chemical components and these are not necessarily the end-members of the diagram. Bases: pymatgen.analysis.phase_diagram.PDEntry This class repesents a TransformedPDEntry, which allows for a PDEntry to be transformed to a different composition coordinate space. 4, Fig. Now, depending on the initial compositions the liquid and the solid phase A or B are in equilibrium with the liquid. information we need to show that we must pass through a two-phase, solid + liquid region as we cool from only liquid to only solid. It is used in the construction of phase diagrams that do not have elements as the terminal compositions. At even lower temperatures an additional phase separation can occur along tangent 2. Mixed compounds are not used in the assignment of chemical systems (with the exception of oxides of elements that are not solids at ambient temperature (e.g., C, N, S, CI), see the Help Page for Chemical System Designation rules). Along a two-phase line in a potential phase diagram the phase corresponding to the higher chemical potential thus must have a larger value on the corresponding molar quantity. However, as long as there is no kinetic barrier to the transition, there is a different state (liquid) available to it in this region and the solid will spontaneously change to the liquid, thus lowering its chemical potential. This can be summarized in a phase diagram like the one shown below. To facilitate the discussion, let’s redraw the last figure with a few points labeled, and compare it to the phase diagram, also redrawn with important points labeled. Phase separate along the tangent 1. possible; and the chemical potential or chemical activity, which describes the effect of compositional change in a solution phase on its energy. This is illustrated by the potential phase diagram in Fig. For full table with Imperial Units - rotate the screen!
All of these thermodynamic quantities are part of the energy content of a system and are governed by the three laws of thermodynamics. Phase Diagram is a generalized module that permits one to calculate, plot and edit unary, binary, ternary and multicomponent phase diagram sections where the axes can be various combinations of T, P, V, composition, activity, chemical potential, etc. Chemical, physical and thermal properties of carbon dioxide: Values are given for gas phase at 25 o C /77 o F / 298 K and 1 atm., if not other phase, temperature or pressure given. There are stable one-phase states of both phases.