Liquid oxygen density temperature correction
The fugacity does not add any new information compared to the chemical potential, but it has computational advantages. As the molar fraction of a component goes to zero, the chemical potential diverges but the fugacity goes to zero. In addition, an ideal gas makes a natural reference state for the fugacity, since the fugacity and pressure converge at low pressure.
The fugacity can be deduced from measurements of volume as a function of pressure at constant temperature. This integral can also be calculated using an equation of state. The integral can be recast in an alternative form using the compressibility factor. This is useful because of the theorem of corresponding states: Then, to a good approximation, most gases have the same value of Z for the same reduced temperature and pressure. However, in geochemical applications, this principle ceases to be accurate at pressures where metamorphism occurs.
For a gas obeying the van der Waals equation , the explicit formula for the fugacity coefficient is. This formula is difficult to use, since the pressure depends on the molar volume through the equation of state; so one must choose a volume, calculate the pressure, and then use these two values on the right-hand side of the equation.
For a pure fluid in vapor—liquid equilibrium, the vapor phase fugacity is equal to the liquid phase fugacity. At pressures above the saturation pressure, the liquid phase fugacity is: The exponential term represents the Poynting correction factor and is usually near 1 unless pressures are very high. Frequently, the fugacity of the pure liquid is used as a reference state when defining and using mixture activity coefficients.
The word fugacity is derived from the Latin for "fleetness", which is often interpreted as "the tendency to flee or escape". The concept of fugacity was introduced by American chemist Gilbert N. From Wikipedia, the free encyclopedia. Electrochemical potential Excess chemical potential Fugacity capacity Multimedia fugacity model Thermodynamic equilibrium.
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