Correction for temperature

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. 

It is always important in thermochemical studies to be aware of the temperature at which the thermochemical properties are determined, and to combine only those properties at the same temperature. Temperature corrections can be made by using integrated heat capacities over the temperature ranges in question. However, it is often assumed that the temperature corrections for ionization energies and electron affinities are small (<1 kJ/mol) and therefore can be neglected. 

The pyrolysis was studied in a toluene carrier flow system over the temperature range 475-603 °C. Most runs were carried out at 16-17 torr with a contact time of 1-2 sec. He ratio % decomposition (gas anaiysis)/% decomposition (antimony recovered from reaction zone) varied from 0.91 at 475 °C to 0.75 at 603 °C. Apparent first-order rate coefficients based on both metal and gas analysis increased with decreasing alkyl concentration (log k/log[Sb(CH3)3] = 0.28 at all temperatures). Corrected for this effect, fc24t0rr/ 6torr = 1-3, indicating a small uni-molecular pressure effect. 

It is convenient that the temperature correction to the enthalpy of reaction 2.2 is rather small, because it suggests that the difference Ar//3io — Ar//298 for reaction 2.1 will also be negligible. In fact, we would be in some trouble to evaluate the temperature correction for the process under the experimental conditions, as some of the necessary data are not readily available. To calculate the solution enthalpies shown in figure 2.1 at 310 K (from the values at 298.15 K), both the (known) values of the heat capacities of the pure substances and the (unknown) values of these quantities in solution are required. 

Recognizing that the enthalpies of vaporization of the higher di-w-alkylzincs are not temperature-corrected for 298 K, and the dimethylzinc and perhaps even the diethylzinc enthalpies are anomalous, we calculate the b substituent constant from the data for... 

Temperature corrections for the atomic enthalpies are also needed in the thermodynamic cycle in Figure 1 to obtain the enthalpy of formation at 298 K or some other temperature. Theoretical enthalpies of formation at 298 K are calculated by correction to AH (0 K) as follows ... 

The accuracy of the ORP measurements depends on the temperature at which a measurement is taken. For solutions with reactions involving hydrogen and hydroxyl ions, the accuracy also depends on the pH of the water. In natural waters, many redox reactions occur simultaneously each reaction has its own temperature correction depending on the number of electrons transferred. Because of this complexity, some of the field meters are not designed to perform automatic temperature compensation. The temperature correction for such meters may be done with a so-called ZoBell s solution. It is a solution of 3 x 10 3 mole (M) potassium ferrocyanide and 2 x 10 2 M potassium ferricyanide in a 0.1 M potassium chloride solution. The Eh variations of the ZoBell s solution with temperature are tabulated for reference, and the sample Eh is corrected as follows ... 

Table 2.10 Temperature Corrections for Water in Borosilicate Glass...

Temperature Corrections for Refractometric Sucrose Solutions with Measurements at 20° and 589 nm... 

We are optimistically generalizing here the findings in J. S. Chickos, D. G. Hesse, S. Y. Panshin, D. W. Rogers, M. Saunders, P. M. Uffer and J. F. Liebman, J. Org. Chem., 57, 1897 (1992) wherein these authors systematically studied the temperature correction for the phase change enthalpy of a set of thermochemically well-characterized hydrocarbons. 

This value is the same as the one in Table B9, and shows that the temperature correction for the heat of reaction is less than 0.2% and is often negligible. The energy expenditure (/< ) at a glucose consumption of 390 g/day is... 

In Chapter 8, along with tables of measured thermophysical data, we saw some fairly simple techniques for estimating these values when experimental results are not available. Among these techniques were Kopp s Rule for the heat capacity of both liquids and solids, and Trouton s ratio for latent heats of fusion and vaporization, along with Kistiakowski s temperature correction for the latter. 

Schrag D. P., Depaolo D. J., and Richter F. M. (1995) Reconstructing past sea surface temperatures—correcting for diagenesis of bulk marine carbonate. Geochim. Cosmochim. Acta 59(11), 2265-2278. 

Table VII presents a comparison of the experimentally derived temperature correction factor to the Berge factor. The calculated Berge factor is based on a temperature coefficient of 9799 recommended in the FTM-2 method. Based on this limited data base, it appears the temperature correction for formaldehyde concentrations is independent of product type, and the Berge calculated factor appears to be about 7-10% too low for a temperature difference greater than 2 C.

Division by the temperature corrects for the changes in modulus due to the inherent dependence of modulus on temperature, while division by the density corrects for the changing number of chains per unit volume with temperature variation. 

Fig. 11-1. Global mean conditions in the world ocean for the following quantities potential temperature 6 (i.e., temperature corrected for adiabatic heating), salinity, concentrations of total C02 and CO, and total alkalinity. [Adapted from Takahashi el al. (1981a).] Dashed curves indicate the spread of total C02 and alkalinity long-dashed curves show the critical dissolution regions for calcite and aragonite according to Broecker and Takahashi (1978).

Table 2.4 lists the calculated volumes for a gram of water in air at atmospheric pressure for different temperatures, corrected for buoyancy with stainless steel weights of density 7.8 g/cm. These are used to give the volume of the glassware... 

Temperature Correction for Glass Volumetric Apparatus 75 Ed. Removed... 

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