Temperature effects volume measurements

The compressibility factor z of methane is always less than 1.0 in normal temperature ranges (i.e., between —40° and 50° C). Furthermore, the compressibility factor decreases as the pressure rises or the temperature falls. Therefore, less energy is needed to pump a given volume of methane (measured at standard volume) at any given normal temperature than would be expected at that temperature if the methane were an ideal gas. This effect is more marked at higher pressures. Similarly, as the pressure is increased at a constant temperature, more methane (measured at standard volume) can be stored in a given volume than would be predicted from the ideal gas equation. 

Any characteristic of a system is called a property. The essential feature of a property is that it has a unique value when a system is in a particular state. Properties are considered to be either intensive or extensive. Intensive properties are those that are independent of the size of a system, such as temperature T and pressure p. Extensive properties are those that are dependent on the size of a system, such as volume V, internal energy U, and entropy S. Extensive properties per unit mass are called specific properties such as specific volume v, specific internal energy u, and specific entropy. s. Properties can be either measurable such as temperature T, volume V, pressure p, specific heat at constant pressure process Cp, and specific heat at constant volume process c, or non-measurable such as internal energy U and entropy S. A relatively small number of independent properties suffice to fix all other properties and thus the state of the system. If the system is composed of a single phase, free from magnetic, electrical, chemical, and surface effects, the state is fixed when any two independent intensive properties are fixed. 

Samples at TMAE concentrations above 0.43M (10% by volume) could be run more than once. This was convenient for measuring temperature effects. We usually began and ended our series with a 0°C. run (Figure 2). As many as seven runs had no apparent effect on k0. No series was run to see when an effect became apparent. Samples at lower concentrations were run only once. Although each such run gave straight decay lines, there was much scatter in the slopes, probably caused by impurity or wall effects. 

Alhedai et a also examined the effect of exclusion on dead volume measurement. A mobile phase consisting of n-octane, the same chain length as the bonded phase, was employed to ensure no differential interaction between the solute and the two phases. A range of aliphatic hydrocarbons from, n-hexane to n-hexaiiiacohtane were chromatographed at two temperature 30°C and 50°C. The two temperatures were used to ensure that the retention mechanism was solely exclusion and not partition. If partition was the mechanism promoting retention, then different retention volumes... 

The temperature effect can also be manipulated. If the temperature is measured at the time the experiment is performed, then the volume of the glassware used can be corrected for the difference between the nominal temperature... 

The trap is loaded in a time of a few seconds, and after a preselected delay its contents are dumped into the resonator region by lowering the field of one of the pinch solenoids. The signal from the hyperfine resonance detector provides a measure of the total number of atoms N in the trap. The stored atoms decay by dipole relaxation (described below) with a rate that is proportional to the density n. From values of N and n one can find the effective volume of the trap. The effective volume depends on the field geometry and the temperature. This roundabout route is... 

Volume measurements needed to calculate the SFI are made by observing and recording the position of the dye solution meniscus in the graduated capillary tube at one temperature (typically 60°C) or two temperatures at which the sample is fully molten, and at desired measurement temperatures (which will be lower than the clear point of the sample). The sample is brought to the first measurement temperature from 0°C after a standardized tempering procedure. This and subsequent measurement temperatures must be approached from below to avoid supercooling effects. Temperature is controlled by immersing the whole dilatometer in constant temperature water baths or an ice-water bath. 

The variation of I3 on e+ exposure illustrates that after prolonged exposure the I3 values can no longer be considered to be related to the number of free volume holes and therefore equation 6 cannot be used. These effects have also lead a number of authors to completely discount the reliability of equation 6 as a measure of the free volume fractions [49, 75, 78, 79]. Other authors have suggested that Eq. 6 may still be used provided the samples are rejuvenated at high temperatures between each measurement [67],... 

Section 12.1 introduces the concept of pressure and describes a simple way of measuring gas pressures, as well as the customary units used for pressure. Section 12.2 discusses Boyle s law, which describes the effect of the pressure of a gas on its volume. Section 12.3 examines the effect of temperature on volume and introduces a new temperature scale that makes the effect easy to understand. Section 12.4 covers the combined gas law, which describes the effect of changes in both temperature and pressure on the volume of a gas. The ideal gas law, introduced in Section 12.5, describes how to calculate the number of moles in a sample of gas from its temperature, volume, and pressure. Dalton s law, presented in Section 12.6, enables the calculation of the pressure of an individual gas—for example, water vapor— in a mixture of gases. The number of moles present in any gas can be used in related calculations—for example, to obtain the molar mass of the gas (Section 12.7). Section 12.8 extends the concept of the number of moles of a gas to the stoichiometry of reactions in which at least one gas is involved. Section 12.9 enables us to calculate the volume of any gas in a chemical reaction from the volume of any other separate gas (not in a mixture of gases) in the reaction if their temperatures as well as their pressures are the same. Section 12.10 presents the kinetic molecular theory of gases, the accepted explanation of why gases behave as they do, which is based on the behavior of their individual molecules. 

Diffusion studies were made using an Isopar M/Heavy Aromatic Naptha (IM/HAN) 9 1 oil mixture (Exxon). Isopar M and HAN are refined paraffinic and aromatic oils, respectively. Figure 3 shows equilibrium salinity scans measured in the laboratory for equal-volume mixtures of the surfactant solution and oil. Since room temperature varied somewhat, the effect of temperature on phase behavior was determined. As Figure 3 shows, there is a small temperature effect, especially at the lower salinities. However, it is not large enough to have influenced the basic results of the contacting experiments. Optimum salinity, where equal volumes of oil and brine are contained in the middle phase, is approximately 1.4 gm/dl. 

UV spectra used for a semi-quantitive determination of the amount of intracrystalline phthalocyanine complexes were taken on a Perkin Elmer UV-visible spectrophotometer. A calibration curve was obtained by dissolving known amounts of metal complex in concentrated sulfuric acid. Zeolite was added to take into account matrix effects. Surface area and pore volume measurements were performed on a Micromeritics ASAP 2000 by absorption of nitrogen gas at liquid nitrogen temperature. X-ray powder diffraction of the zeolites was used to ensure good crystallinity after the exchange and encapsulation procedures... 

---