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Triple point: defined

Temperature kelvin K Defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. [Pg.77]

The ultimate definition of thermodynamic temperature is in terms of pV (pressure X volume) in a gas thermometer extrapolated to low pressure. The kelvin (K), the unit of thermodynamic temperature, is defined by specifying the temperature of one fixed point on the scale—the triple point... [Pg.1214]

Defining fixed points of the International Temperature Scale of 1990 (ITS-90). Except for the triple points, the assigned values of temperature are for equilibrium states at a pressure of one standard atmosphere (101 325 Pa). [Pg.1218]

Temperature. Temperature maybe measured on an absolute or relative scale. The two most common relative scales are the Celsius and the Fahrenheit scales. The Celsius scale is defined as 0°C at the freezing point (triple point) of water and 100°C at the boihng point. The Fahrenheit scale is arbitrarily defined by assigning it a temperature of 32 degrees at the freezing point of water and 212°F at the boihng point of water (see Temperature measurements). [Pg.309]

For many purposes in chemistry, the most convenient unit of temperature is the ketvin (K) note the absence of the degree sign. The kelvin is defined to be 1/273.16 of the difference between the lowest attainable temperature (0 K) and the triple point of water (0.01°C). The relationship between temperature in K and in °C is... [Pg.9]

Temperature Tgo in the range between 3.0 and 24.5561 K is defined in terms of 3He or 4He constant volume gas thermometers (CVGT), calibrated at the triple points of Ne and H2, and at a temperature between 3.0 and 5.0 K that has been obtained from vapor pressure versus temperature relations for He. [Pg.620]

In the temperature range between 4.2 and 24.5561 K (triple point of neon), is defined by the equation... [Pg.620]

FIGURE 8.6 The phase diagram for water (not to scale). The solid blue lines define the boundaries of the regions of pressure and temperature at which each phase is the most stable. Note that the freezing point decreases slightlv with increasing pressure. The triple point is the point at which three phase boundaries meet. The letters A and B are referred to in Example 8.3. [Pg.436]

A triple point is a point where three phase boundaries meet on a phase diagram. For water, the triple point for the solid, liquid, and vapor phases lies at 4.6 Torr and 0.01°C (see Fig. 8.6). At this triple point, all three phases (ice, liquid, and vapor) coexist in mutual dynamic equilibrium solid is in equilibrium with liquid, liquid with vapor, and vapor with solid. The location of a triple point of a substance is a fixed property of that substance and cannot be changed by changing the conditions. The triple point of water is used to define the size of the kelvin by definition, there are exactly 273.16 kelvins between absolute zero and the triple point of water. Because the normal freezing point of water is found to lie 0.01 K below the triple point, 0°C corresponds to 273.15 K. [Pg.438]

We wish to mention the recent proposal for a redefinition of Kelvin in terms of mechanical units through the Boltzmann constant [6-7] the Kelvin should be defined as the unit of thermodynamic temperature such that the value of the Boltzmann constant is 1.3806505 x 10 23 JK 1 exactly. Of course, this value of the Boltzmann constant should be consistent with a thermodynamic temperature of the triple point of water of 273.16 K. [Pg.191]

Between the triple point of equilibrium hydrogen (13.8033 K) and the freezing point of silver (1234.93 K), Tgo is defined by means of platinum resistance thermometers calibrated at specific sets of defining fixed points. The temperatures are given in terms of the ratio of the resistance of the thermometer at temperature Tgo to the resistance at the triple point of water ... [Pg.304]

In a similar way, the Systeme Internationale has defined other common physicochemical variables. The SI unit of temperature T is the kelvin. We define the kelvin as 1/273.16th part of the thermodynamic temperature difference between absolute zero (see Section 1.4) and the triple point of water, i.e. the temperature at which liquid water is at equilibrium with solid water (ice) and gaseous water (steam) provided that the pressure is 610 Pa. [Pg.16]

Following an international convention [3], if we take the temperature of the triple point of water as a reference temperature (Tq) and assign it the value of 273.16 K on the absolute scale, then any other ideal gas temperature T is defined by the equation... [Pg.33]

The Krafft Point may be defined as the temperature above which the solubility of a surfactant increases steeply. At this temperature, the solubility of the surfactant becomes equal to the critical micelle concentration (Cj ) of the surfactant. Therefore, surfactant micelles only exist at temperatures above the Krafft Point. This point is a triple point at which the surfactant coexists in the monomeric, the micellar, and the hydrated solid state (, ). [Pg.4]

By combining the various observations obtained from the G-T diagrams in different P conditions, we can build up a P-P diagram plotting the stability fields of the various polymorphs, as shown in figure 2.5. The solid dots in figures 2.4 and 2.5 mark the phase transition limits and the triple point, and conform to the experimental results of Richardson et al. (1969) (A, R, B, C ) and Holdaway (1971) (A, H, B, C). The dashed zone defines the uncertainty field in the... [Pg.104]

The phase diagram also illustrates why some substances which melt at normal pressure, will sublime at a lower pressure the line p = Pa intersects at Tg the locus OR of the points defining the solid-vapour equilibrium, i.e. at the pressure pj, the substance will sublime at the temperature T. Sometimes the opposite behaviour is observed, namely that a substance which sublimes at normal pressure will melt in a vacuum system under its own vapour pressure This is a non-equilibrium phenomenon and occurs if the substance is heated so rapidly that its vapour pressure rises above that of the triple point this happens quite frequently with aluminium bromide and with iodine. [Pg.15]

Temperature kelvin (K) Temperature is defined such that the triple point of water (at which solid, liquid, and gaseous water are in equilibrium) is 273.16 K, and the temperature of absolute zero is 0 K. [Pg.9]

Karl Fischer titration A sensitive technique for determining water, based on the reaction of HzO with an amine, I2, S02, and an alcohol, kelvin, K Absolute unit of temperature defined such that the temperature of water at its triple point (where water, ice, and water vapor are at equilibrium) is 273.16 K and the absolute zero of temperature is 0 K. Kieselguhr German term for diatomaceous earth, which was formerly used as a solid support in gas chromatography. [Pg.695]

Heat and temperature were poorly understood prior to Carnot s analysis of heat engines in 1824. The Carnot cycle became the conceptual foundation for the definition of temperature. This led to the somewhat later work of Lord Kelvin, who proposed the Kelvin scale based upon a consideration of the second law of thermodynamics. This leads to a temperature at which all the thermal motion of the atoms stops, By using this as the zero point or absolute zero and another reference point to determine the size of the degrees, a scale can be defined. The Comit e Consultative of the International Committee of Weights and Measures selected 273.16 K as the value lor the triple point for water. This set the ice-point at 273.15 K. [Pg.3]

Kelvin (degree Kelvin) K Defined in the thermodynamic scale by assigning 273.16 K to the triple point of water (freezing point, 273.15 K = 0°C)... [Pg.970]

For example for a two-phase (p = 2) water-ice (c = 1) system we have only one degree of freedom (/ = 1). Thus, we can change the temperature of water and still have coexisting ice, but only at one given pressure. This is the melting point (temperature) A (Fig. A.2) that lies on the coexistence line. If we move to point A we are in the water phase (p = 1) and according to (A.35) we now have two degrees of freedom (/ = 2), temperature and pressure. This triple point is where all three phases coexist (p = 3) it is uniquely defined (/ = 0). This temperature is the official zero of the Celsius scale. [Pg.348]


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See also in sourсe #XX -- [ Pg.307 ]




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