Boyle Point

Boyle Point

 

the minimum point on an isotherm of a real gas, represented in (p, pV) coordinates. (See Figure 1; ρ is the pressure of the gas and V is the volume occupied by the gas.) It is named for the English scientist R. Boyle.

Figure 1. Isotherms of a real gas [in (p, pV) coordinates] that characterize the compressibility of the gas. T0, is the Boyle temperature; Boyle points are absent on isotherms with temperature T > TB.

In the vicinity of the Boyle point, small sections of the isotherm of a real gas can be considered approximately as segments of horizontal straight lines that according to the Clapeyron equation pV = mRT represent the isotherms of an ideal gas. (T is the absolute temperature, R is the gas constant, and m is the mass of the gas.) In other words, the Boyle point determines the temperature at which, for a given real gas, the equation of an ideal gas is applicable. The section of the isotherm ab (to the left of the Boyle point) corresponds to the conditions under which a real gas is more compressible than an ideal gas; the section bc (to the right of the Boyle point) corresponds to the conditions of lower compressibility of a real gas in comparison with an ideal gas. The dominant influence of the forces of attraction between molecules, which facilitates the contraction of a gas, becomes apparent to the left of the Boyle point; the influence of the volume of the molecules themselves, which hinders contraction, appears to the right of the Boyle point. In the vicinity of the Boyle point, these factors—which distinguish a real gas from an ideal gas—compensate each other.

The line that connects the Boyle points of individual isotherms is called the Boyle curve. The point of this curve that lies on the y-axis (p = 0) determines the so-called Boyle temperature (TB). For a gas that obeys the van der Waals equation, TB = 3.375 Tc, where Tc is the critical temperature. For T < Tc the complete liquefaction of the gas under pressure is possible; for T < TB, partial liquefaction of gases is possible upon throttling.

IU. N. DROZHZHIN

References in periodicals archive ?
There was a significant moment late on when James Murray, stand-in skipper in the absence of the suspended Daryl Flynn and vice-captain David Whyte, dived on a Conor Boyle point effort to pull off a heroic block.
BC Ferries run across Baynes Sound to Denman Island, where sea lions raft together and drift off Boyle Point Provincial Park.
A good Brian Kavanagh point helped Longford back into the game at 0-6 to 0-3 before a Conor Boyle point late in the first half helped Laois to a six-point lead at half-time.
Down made a brave effort and came back with a Boyle point but the same player missed an easy free and with that went any chance of salvaging something from the game
Boyle points out that there have been several new FDA-approved formulations in the past few years that can help reduce some of the side effects.
Boyle's approach yields insightful observations about the multiple mediations of a text such as The BlazingWorld, which is, Boyle points out, anamorphically joined to its philosophical companion, Observations Upon Experimental Philosophy.
But Boyle points out, quite rightly, that even a piece of writing as utilitarian as a police report must have a set of background assumptions and expectations to which it appeals when reporting an incident in the manner that it does: what counts as a law, when are laws bent or broken, who counts as a plausible witness, when is it appropriate to lay praise or blame on someone, and so on.
Whereas Wotashirtfull and Step It Up are both in-form five-furlong specialists, there are negatives against both of their opponents, as Boyle points out.
Careful analysis of this data is obvious to anyone with a scientific interest in the subject but, as Boyle points out, the average punter does not operate scientifically.
As Matthew Boyle points out in his report, this generation is very market-savvy and knows when it's being sold to--and doesn't much like it.