Temperature corrections

In those cases where the literature Kc values were at a temperature T other than 298 K, the InA c versus HT relationship was assumed to be linear and Kc at 25 °C was calculated from 

Examples of the effect of a temperature change from 20 to 25 °C on pATbij values are given in Table 5.3. The p/fsh of Lewis bases is seen to vary slightly with temperature. Hence it is not necessary to know the exact complexation enthalpy to apply a temperature correction. It is sufficient to estimate the complexation enthalpy from data pertaining to closely related Lewis bases. 

The measurement of diiodine complexation constants has generally been performed in alkanes or chlorinated solvents. It has been observed [63] that the value of the equilibrium 

The inert, UV-transparent, low-toxic and common solvent heptane is the solvent of choice for evident technical and theoretical reasons. Its major limitation is the difficulty of solubilizing Lewis bases and diiodine complexes that are strongly dipolar. It may then be necessary to use media of a greater solubilization power than heptane, for example cyclohexane, CCI4, CH2CI2 and CHCI3. 

The comparison, made in Table 5.4, of values measured in heptane and in other alkanes (cyclohexane, hexane, methylcyclohexane) for a set of 30 diverse bases, shows that the differences are generally within the sum of experimental uncertainties. In the following, the Kc values measured in cyclohexane, hexane and methylcyclohexane will therefore be considered equivalent to, and will be mixed with, those measured in heptane. 

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The results are presented as a distillation curve showing the boiling temperature (corrected to atmospheric pressure) as a function of the distilled volume. 

Table 2.9 Barometer Temperature Correction—Metric Units 2.72...

The Ubbelohde viscometer is shown in Figure 24c. It is particularly useful for measurements at several different concentrations, as flow times are not a function of volume, and therefore dilutions can be made in the viscometer. Modifications include the Caimon-Ubbelohde, semimicro, and dilution viscometers. The Ubbelohde viscometer is also called a suspended-level viscometer because the Hquid emerging from the lower end of the capillary flows down only the walls of the reservoir directly below it. Therefore, the lower Hquid level always coincides with the lower end of the capillary, and the volume initially added to the instmment need not be precisely measured. This also eliminates the temperature correction for glass expansion necessary for Cannon-Fen ske viscometers. 

The concentration of dissolved ionic substances can be roughly estimated by multiplying the specific conductance by an empirical factor of 0.55—0.9, depending on temperature and soluble components. Since specific conductance is temperature dependent, all samples should be measured at the same temperature. Alternatively, an appropriate temperature-correction factor obtained by comparisons with known concentrations of potassium chloride may be used. Instmments are available that automatically correct conductance measurements for different temperatures. 

A general relation for Hl which may be used as the basis for applying temperature corrections is as follows ... 

The mercury barometer (Fig. 10-11) indicates directly the absolute pressure of the atmosphere in terms of height of the mercuiy column. Normal (standard) barometric pressure is 101.325 kPa by definition. Equivalents of this pressure in other units are 760 mm mercury (at 0°C), 29.921 iuHg (at 0°C), 14.696 IbFin, and 1 atm. For cases in which barometer readings, when expressed by the height of a mercuiy column, must be corrected to standard temperature (usually 0°C), appropriate temperature correction factors are given in ASME PTC, op. cit., pp. 23-26 and Weast, Handbook of Chemistty and Physics, 59th ed., Chemical Rubber, Cleveland, 1978-1979, pp. E39-E41. 

Winding temperature measurement at site 10/241 10.6.1 Temperature correction 10/241... 

Table 11.2 Permissible stopping period of the motor after shutdown when it will reguire no temperature correction...

The calculation procedure for temperature correction factors won t work for a temperature cross in a single shell pass, but this is an undesirable situation anyway. 

The refractive indices of most essential oils have been given under each oil in Volume I. if a temperature correction is required, as it frequently is, the addition of 0-0C04 for each degree centigrade by which it is necessary to reduce the temperature, and a similar subtraction for a rise of 1°, should be made. This figure varies slightly, but unless accuracy to the fifth place of decimals is required, it is sufSciently accurate for practical purposes. 

Temperature correction factor, vacuum flow. Figure 2-43... 

Table 7-10 pre.sents a temperature conversion table for various metals from one manufacturer for conventional pre-bulged, ten-sion-loaded disks with pressure on concave side (not prescored) as an illustration of the effect of lower or elevated temperatures referenced to 72°F on the burst pressure of a stamped disk. For other types of disk designs and from other manufacturers, the specific data for the style disk must be used to make the appropriate temperature correction. 

TEMPERATURE CORRECTION FACTOR IN % FROM RUPTURE PRESSURE AT 72T. 

If the temperature at the valve inlet is expected to be 50°F, then the temperature correction factor... 

The SpGr correcdon factor = 1.0518 (interpolated) and the temperature correction at 55°F = 1.0048 both are from Table 7-16. 

Gravity and Temperature Correction Factors for Low Pressme Venting Calculations for Vapors... 

SpGr correction = (2.69) 72 = 154 Temperature correction = 0.9551 from Table 7-16 The volume at standard conditions of 14.7 psia and 60°F ... 

For negative pressure less than 20 in. WG, the correction is considered negligible. Referring to Table 12-14C, the correction factors for negative static pressure, at SP in Table, select factor (Fg), the corrected static pressure (SP) = (Fg) (required fan static pressure output based on temperature corrected SPofPar. (a)). 

Chart II Temperature Correction Factors for Maximum Safe Speeds of LS or RIM Wheels... 

Chart III Temperature Corrections Factors for Maximmn Safe Speeds of DH Wheels... 

In the use of graduated glassware for measurement of the volume of liquids, the expansion of the liquid must also be taken into consideration if temperature corrections are to be made. Part B of Table 3.1 gives the corrections to be added or subtracted in order to obtain the volume occupied at 20 °C by a volume of water which at the tabulated temperature is contained in an accurate lOOOmL flask having a standard temperature of 20 °C. It will be seen that the allowance for the expansion of water is considerably greater than that for the expansion... 

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