triple point

(redirected from triple points)
Also found in: Dictionary, Medical.

triple point

Chem the temperature and pressure at which the three phases of a substance are in equilibrium. The triple point of water, 273.16 K at a pressure of 611.2 Pa, is the basis of the definition of the kelvin

Triple Point

 

in thermodynamics, the point on a phase diagram at which three different phases of a substance can coexist in equilibrium.

It follows from the phase rule that there cannot be more than three phases in equilibrium in a substance consisting of one chemical element or compound, that is, a one-component system. The three phases may be, for example, the solid, liquid, and gas phases or, as in the case of sulfur, the liquid phase and two al-lotropes of the crystalline phase. The phases can coexist only for specific values of temperature T and pressure p, which determine the coordinates of the triple point on the p-T diagram.

For example, for carbon dioxide the triple-point temperature Ttp = 216.6°K, and the triple-point pressure ptp = 5.12 atmospheres. At the triple point of water, which is the fundamental fixed point of the absolute thermodynamic temperature scale, Ttp = 273.16°K (exactly), and ptp = 4.58 mm Hg.

triple point

[′trip·əl ′pȯint]
(physical chemistry)
A particular temperature and pressure at which three different phases of one substance can coexist in equilibrium.
References in periodicals archive ?
With triple points, up to 50,000, on all qualifying stays through January 15, our members can earn enough points for their next vacation with family or friends, or make this year's shopping easier by redeeming for over 200 gift card options.
To be eligible for triple points you must book and stay before 20 December 2013.
By offering triple points, we're able to help our members achieve a reward three times as fast.
The Club Carlson Triple Points Returns promotion provides our members with an exciting way to start 2013," said Mary Kay Caschetta, vice president, Loyalty, Americas.
Now, with the holiday season upon us, we have created another way of saying thank you to our Emperor's Club members by offering triple points when they dine at a participating Benihana restaurant on Thanksgiving Day," said Kevin Aoki, Benihana vice president of marketing.
For the Royal Bank program, selected cardholders will receive triple points on their second visit, quadruple points on their third visit, and so on (until ten times the points).
Marriott Hotels Marriott Rewards Award: up to triple points Expires: 12/31/2010 Restrictions: Marriott's Meetings Matter: Earn double points up to 100,000 total points on qualifying charges per meeting or event or earn triple points when paying with a Visa.