Partial Pressure

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partial pressure

[′pär·shəl ′presh·ər]
The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container.

Partial Pressure


In a mixture of gases that occupies a certain volume, the partial pressure of each component gas is the pressure the gas would have if it alone occupied the same volume at the same temperature. Dalton’s law states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the mixture’s components. A gas’s partial pressure determines the course of the processes of diffusion, absorption, and solution of the gas, as well as of the distribution of the gas between two parts of a system where the parts are separated by a partition that is permeable to the gas.

References in periodicals archive ?
To the vacuum practitioner, total pressure is the sum of the partial pressures of the various gases making up the vacuum environment.
(1994) studied the influence of [H.sub.2]S partial pressure on the activity of model Mo[S.sub.2]/A[L.sub.2][O.sub.3] over a wide range of [H.sub.2]S partial pressure from 0-0.3 MPa, under a total pressure of 6 MPa, at 320-410[degrees]C and 0.5-0.7 [h.sup.-1].
Managing water vapor in a vacuum chamber by adding a supplemental water vapor cryopump and cryocoil can cut pumpdown time, increase product throughput, and lower water vapor partial pressure during processing for high quality, better adhesion, and more reproducible deposition.
For example, in the lung bases where alveoli are better perfused than ventilated, the P[O.sub.2] tensions in the blood tend to be low and the PC[O.sub.2] partial pressures are predisposed to be higher.
Process specifications are usually established in terms of a target total pressure or partial pressures of specific problem gases before the process is initiated.
These are called contamination resulting in additional partial pressure (CRAPP).
A Faraday cup detector is standard with both systems, allowing partial pressure measurements from [10.sup.-5] to [10.sup.-8] torr.
Once base vacuum is reached and deposition commences, the high-speed pumping of water vapor must continue if residual water vapor partial pressure is to be kept low in the face of its continual outgassing.
In either case, detector output is proportional to the partial pressure of the particular gas species that traversed the mass filter.
Another of these "smart" RGAs is the Partial Pressure Transducer (PPT), from the NGS Div.
They showed that background partial pressures in an ultrahigh vacuum sputtering system can be reduced by an order of magnitude when the system is pumped with a cryogenic pump, rather than a slower turbomolecular pump.
The increase in temperature caused considerable changes in the partial pressures of [O.sub.2] and C[O.sub.2] inside the packages during the storage period.

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