Ice-point

Emf values are given vs the reference-grade platinum of NIST (NBS Pt27) with the cold junction at the ice point. 

Glass-creep errors are also encountered. The Hquid-in-glass thermometer should always be used to measure temperatures in ascending order. If the thermometer is stored at room temperature, a temporary ice point depression results, which may be as much as 0.01 K for 10 K of temperature difference, when the thermometer is heated above room temperature. If the thermometer is used to measure a temperature and must then be used to measure a lower temperature, the thermometer should be stored at a stiH lower temperature for at least 3 days prior to use to assure recovery of bulb dimensions. 

Because the system likely is nonisothermal, the analysis of a closed-desiccant system requites knowledge of the temperature of the desiccant as well as the dew point (ice point) or water concentration (partial pressure) specification. Indeed, the whole system may undergo periodic temperature transients that may compHcate the analysis. Eor example, in dual-pane windows the desiccant temperature is approximately the average of the indoor and outdoor temperatures after a night of cooling. However, after a day in the sun, the desiccant temperature becomes much warmer than the outdoor temperature. When the sun sets, the outdoor pane cools quickly while the desiccant is still quite warm. The appropriate desiccant for such an appHcation must have sufficient water capacity and produce satisfactory dew points at the highest temperatures experienced by the desiccant. 

If the temperature of 1 mL of air at 1 atm and 0°C is raised to 100°C at the same pressure, the volume becomes 1.3671 mL. Calculate the value of absolute zero for a thermometer using air, assuming that the pressure-volume product is linear with absolute temperature even at 1 atm. Compare your result with the ice-point temperature in Table 2.3. 

Calibration of thermocouples should be carried out at two temperatures. One of these is an ice-point reference at 0.0°C. The other should be a hot point slightly higher than the expected sterilization temperature. Correction factors are applied at both temperatures and the response of... 

Ice point temperature Molar gas constant Avogadro constant... 

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. 

Effects of Thermal Energy Thermal conductivity Melting and boiling point determinations Ice point-humidity instrumentation, among others Dew point-humidity instrumentation, among others Vapor pressure Fractionation C liro matography Tliermal expansion... 

FAHRENHEIT TEMPERATURE SCALE (abbr F). A temperature scale with the ice point at 32 and the boiling point of water at 212. Conversion with the Celsius "centigrade temperature scale (ubbrC) is by the formula... 

ICE POINT. The temperature at which, a mixture of air-saturated pure water and pure ice may exist in equilibrium at a pressure of one standard atmosphere,... 

The values of the constants in the Uiermometric function are determined with reference to fixed thermometnc points whose temperatures are arbitrarily assumed. The fixed thermometric points most frequently employed are the ice point, steam point and triple point of water. 

A Centigrade (or Celsius) temperature scale is obtained by choosing the thennoraetric function, Equation (3), and assigning die following arbitrary values of temperature, 0, to die ice point [0, i and steam point (ft ) respectively... 

Different empirical temperature scales will naturally differ from each other except at the respective fixed thermometnc points, Even different scales of the same type (say different Centigrade scales) will differ at all temperatures, except the steam point and ice point, depending on the fortuitous properties of the system chosen as a thermometer. It is, therefore, necessary to remove these differences and to obtain a more universal scale. This has been achieved in two ways. The practical way of achieving uniformity is to lay down detailed rules concerning the thermometer (actually different thermometers depending on the range of temperatures to be measured). Such rules have been agreed on internationally and... 

However, unlike Davy s experiments, Priestley s temperature (17°F) of the gas mixture was below the ice point, so there is no unequivocal evidence that the frozen system was hydrate. There is also no record of validation experiments by Priestley consequently, Davy s independent discovery of chlorine hydrate is generally credited as the first observance. 

Villard (1896) proposed an indirect macroscopic method to determine hydration number, which uses the heat of formation, both above and below the ice point. In his review, Schroeder (1927) indicates that after 1900, researchers abandoned direct measurement of hydrate phase composition, preferring Villard s method (see Section 4.6.2) that relies on easier measurements of pressure and temperature. Miller and Strong (1946) provided another thermodynamic method to determine hydration number, discussed in Section 4.6.2.2. 

In the mid-1930s Hammerschmidt studied the 1927 hydrate review of Schroeder (D.L. Katz, Personal Communication, November 14, 1983) to determine that natural gas hydrates were blocking gas transmission lines, frequently at temperatures above the ice point. This discovery was pivotal in causing a more pragmatic interest in gas hydrates and shortly thereafter led to the regulation of the water content in natural gas pipelines. 

The heat of dissociation (A77d) is defined as the enthalpy change to dissociate the hydrate phase to a vapor and aqueous liquid, with values given at temperatures just above the ice point. To a fair engineering approximation AZ/d is... 

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