Definitions for fugacityfyuˈgæs ɪ ti
This page provides all possible meanings and translations of the word fugacity
Random House Webster's College Dictionary
Bot. falling or fading early.
Origin of fugacious:
1625–35; < L fugāx apt to flee, fleet, der. of fugere to flee; see -acious
fu•gac•i•tyfyuˈgæs ɪ ti(n.)
the tendency of a gas to expand or escape
the lack of enduring qualities (used chiefly of plant parts)
A measure of the tendency of a fluid to expand or escape
A measure of the relative stability of different phases of a substance under the same conditions
the quality of being fugacious; fugaclousness; volatility; as, fugacity of spirits
In chemical thermodynamics, the fugacity of a real gas is an effective pressure which replaces the true mechanical pressure in accurate chemical equilibrium calculations. It is equal to the pressure of an ideal gas which has the same chemical potential as the real gas. For example, nitrogen gas at 0°C and a pressure of has a fugacity of . This means that the chemical potential of real nitrogen at a pressure of 100 atm is less than if nitrogen were an ideal gas; the value of the chemical potential is that which nitrogen as an ideal gas would have at a pressure of 97.03 atm. Fugacities are determined experimentally or estimated from various models such as a Van der Waals gas that are closer to reality than an ideal gas. The ideal gas pressure and fugacity are related through the dimensionless fugacity coefficient . For nitrogen at 100 atm, the fugacity coefficient is 97.03 atm / 100 atm = 0.9703. For an ideal gas, fugacity and pressure are equal so is 1. The contribution of nonideality to the chemical potential of a real gas is equal to RT ln . Again for nitrogen at 100 atm, the chemical potential is μ = μid + RT ln 0.9703, which is less than the ideal value μid because of intermolecular attractive forces.
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