Gases refractive index

The transition between crystalline and amorphous polymers is characterized by the so-called glass transition temperature, Tg. This important quantity is defined as the temperature above which the polymer chains have acquired sufficient thermal energy for rotational or torsional oscillations to occur about the majority of bonds in the chain. Below 7"g, the polymer chain has a more or less fixed conformation. On heating through the temperature Tg, there is an abrupt change of the coefficient of thermal expansion (or), compressibility, specific heat, diffusion coefficient, solubility of gases, refractive index, and many other properties including the chemical reactivity. 

Colorless and odorless gas refractive index 1.000036 at 0°C and 1 atm density of the gas at 0°C and 1 atm 0.1785 g/L density of hquid hehum at its boihng point 0.16 g/mL liquefies at -268.93°C sohdifies at -272.2°C (at 26 atm) to a crystalline, transparent and almost invisible sobd having a sharp melting point cannot be solidified at the atmospheric pressure except by lowering temperatures critical temperature -267.96°C critical pressure 2.24 atm critical volume 57cm3/mol very slightly soluble in water solubility in water 0.0285 mg/L (calculated) at 25°C or 0.174 mL/L at NTP insoluble in ethanol. 

Laser interferometer setup for gas refractive index determination. 

Gas-handling system for gas refractive index determination. Many connections are made with Swagelok and/or Ultra-Torr fittings. The HCI lecture bottle must be securely fastened to the laboratory bench. 

For an air/glass interface, tan 0b = n, the refractive index of glass. In a gas laser, the light must be reflected back and forth between mirrors and through the gas container hundreds of times. Each time the beam passes through the cavity, it must pass through transparent windows at the ends of the gas container (Figure 18.10b), and it is clearly important that this transmission be as efficient as possible. 

Solution Polymers. Acryflc solution polymers are usually characterized by their composition, solids content, viscosity, molecular weight, glass-transition temperature, and solvent. The compositions of acryflc polymers are most readily determined by physicochemical methods such as spectroscopy, pyrolytic gas—liquid chromatography, and refractive index measurements (97,158). The solids content of acryflc polymers is determined by dilution followed by solvent evaporation to constant weight. Viscosities are most conveniently determined with a Brookfield viscometer, molecular weight by intrinsic viscosity (158), and glass-transition temperature by calorimetry. 

Formula GAS Registry Number Molecular weight Boiling poiut, °G Melting poiut, °G Liquid density, g/mL at °G Refractive index, n- at °G... 

Table 4 lists the specifications set by Du Pont, the largest U.S. producer of DMF (4). Water in DMF is deterrnined either by Kad Fischer titration or by gas chromatography. The chromatographic method is more rehable at lower levels of water (<500 ppm) (4). DMF purity is deterrnined by gc. For specialized laboratory appHcations, conductivity measurements have been used as an indication of purity (27). DMF in water can be measured by refractive index, hydrolysis to DMA followed by titration of the Hberated amine, or, most conveniendy, by infrared analysis. A band at 1087 cm is used for the ir analysis. 

When simple Hquids like naphtha are cracked, it may be possible to determine the feed components by gas chromatography combined with mass spectrometry (gc/ms) (30). However, when gas oil is cracked, complete analysis of the feed may not be possible. Therefore, some simple definitions are used to characterize the feed. When available, paraffins, olefins, naphthenes, and aromatics (PONA) content serves as a key property. When PONA is not available, the Bureau of Mines Correlation Index (BMCI) is used. Other properties like specific gravity, ASTM distillation, viscosity, refractive index. Conradson Carbon, and Bromine Number are also used to characterize the feed. In recent years even nuclear magnetic resonance spectroscopy has been... 

Experimental determinations are far from straightforward, especially if the molecule has little or no symmetry. The mean value can be deduced from the refractive index of a gas, whilst Kerr effect experiments give some idea of the anisotropy. 

Ethyl Benzoate.—This ester has not been found, so far, to occur naturally in essential oils. It has, however, been prepared by synthetic processes, for example, by condensing ethyl alcohol with benzoic acid by means of dry hydrochloric acid gas. Its odour is very similar to that of methyl benzoate (q.v.), but not quite so strong. It is an oil of specific gravity I OfilO, refractive index 1 5055, and boiling-point 213° at 745 mm. It is soluble in two volumes of 70 per cent, alcohol. 

Ethyl Cinnamate.—The cinnamic ester of ethyl alcohol is a natural constituent of a few essential oils, including camphor oil and storax. It is formed synthetically by condensing cinnamic acid and ethyl alcohol by dry hydrochloric acid gas. It has a soft and sweet odour, and is particularly suitable for blending in soap perfumes. It is an oil at ordinary temperatures, melting at 12°, and boiling at 271°. Its specific gravity is 1 0546, and its refractive index 1 5590. 

Aniline point is used in some correlations to estimate the aromaticity of gas oil and light stocks. TOTAL S [1] correlation uses aniline point and refractive index. Others, such as n-d-M [2], employ refractive index to characterize FCC feed. 

Plot the feed refractive index, API gravity, and aniline point. Determine any shift in the amount of cracked gas oil in the feed. 

Using the ideal gas law and the relationship (n — 1) oc p between refractive index n and density p leads us to the refractive index structure function. 

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