Density ethanol—water mixtures

Most frequently, volume data for solutions are tabulated as density p as a function of composition. The procedure for obtaining y i2 is illustrated by reference to the densities and weight percent concentrations of ethanol-water mixtures (Table 18.1, Columns 1 and 4 at 25°C). 

TABLE 18.1. Densities and Partial Volumes of Ethanol-Water Mixtures"... 

The density of the liquid mixture can be determined using a pyknometer or it can be derived from a previously determined calibration curve. For the determination of densities less than unity (e.g., polyethylene), ethanol/water mixtures are suitable for densities larger than unity one may use mixtures of water with aqueous salt solutions (40% CaCl2 solution = 1.40 g/ml 72% ZnCl2 solution = 1.95 g/ml). The density gradient method, which is an elegant var-... 

A test set of 6 to 13 aroma compound partition coefficients between different food contact polymers (low density polyethylene (LDPE), high density polyethylene (HDPE) polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA)) and different food simulant phases (water, ethanol, aqueous ethanol/water mixtures, methanol, 1-propanol) were taken from the literature (Koszinowski and Piringer, 1989, Baner, 1992, Franz, 1990, Koszinowski, 1986, Franz, 1991, Baner, 1993, Piringer, 1992). Table 4-2 shows the test set of 13 different aroma compounds, with their properties and their structures. The experimental data were compared to estimations using different estimation methods of UNIFAC-FV, GCFLORY (1990), GCFLORY (1994) and ELBRO-FV. 

New tables of practical laboratory data such as Flame and Bead tests. Flame Temperatures, and Density of Ethanol-Water Mixtures... 

Although density measurements of varying degrees of accuracy have been reported for ethanolic solutions, standard state partial molal volumes in ethanol have been evaluated for only a few electrolytes. Vosburgh, Connell and Butler reported for LiCl in water and a series of alcohols, including ethanol. They observed that the salt had a much smaller value of F in the alcohols than in water, and that for all the systems studied it was smallest in ethanol. Sobkowski and Mine have reported for HCl in water and the three lower alcohols and also observe F to be smaller in the alcohols than in water, but it is smallest in methanol rather than ethanol. Lee and Hyne have reported F° at 50.25°C for the tetraalkylammonium chlorides in ethanol-water mixtures up to 0.4 mol fraction of ethanol. With the tetramethyl and tetraethyl salts, the volumes are all very positive in water but decrease rapidly with an increase in alcohol content and appear to be at a minimum around 0.3 to 0.4 mol fraction of ethanol. The higher tetraalkyl salts are not entirely consistent with this pattern. 

Table 6.49 Densities of Pure Ethanol-Water Mixtures at Various Temperatures (19)...

Extractable di-(2-ethylhexyl) phthalate, DOP, is determined in plastic collapsible containers for human blood and blood components. A sample of plastic is extracted with ethanol-water mixture having a density of 0.937 at 37°C for 60 min. The resultant solution is measured for absorbance at 272 nm and concentration of plasticizer determined from calibration curve. 

The errors caused by this simplification are usually small The largest error has been reported for the ethanol-water mixture, where the contribution of the excess volume can arise up to 3.5% [17]. It is worth mentioning that Eq. (3.60) yields better results than a linear mixing rule for the density, which is often applied due to its simplicity, especially when the pure component densities are significantly different. 

Similarly, based on density and sound velocity measurements, Parke and Birch [88] reported apparent specific volume and apparent specific isenttopic compressibility curves for the ethanol/water mixture. They observed a shallow minimum in the apparent specific isentropic compressibility curves at Xi 0.05 and an increase afterwards, which generally conforms to the situation presented in Figure 6.5. 

An ethanol/water mixture containing 44.00 wt-% of ethanol C2H5OH, has the density 0.93069 g/cm at 15 °C. At the same temperature the density of undiluted ethanol and water is 0.79365 g/cm and 0.99910 g/cm , respectively. Estimate the reduction in volume when ethanol and water are mixed in this proportion ... 

The O H stretching spectra of ethanol trimers and larger clusters cannot be conformationally resolved in a slit jet expansion [65, 77, 157], VUV-IR spectra [184] are even broader, sometimes by an order of magnitude, and band maxima deviate systematically by up to +50 cm 1 from the direct absorption spectra. We note that ethanol dimers and clusters have also been postulated in dilute aqueous solution and discussed in the context of the density anomaly of water ethanol mixtures [227], Recently, we have succeeded in assigning Raman OH stretching band transitions in ethanol-water, ethanol water, and ethanol water2 near 3550, 3410, and 3430cm, respectively [228],... 

In Ref 4 is described a rapid method for dem of the amount of EtAcet ethanol in their mixtures with water, accdg to the density and water content as detd by the Fischer Method... 

The reactor will be charged with a mixture containing 500 kg/m3 ethanol and 250 kg/m3 acetic acid, the remainder being water, and a small quantity of hydrochloric acid to act as a catalyst. The density of this mixture is 1045 kg/m3 which will be assumed constant throughout the reaction. The reaction is reversible with a rate equation which, over the concentration range of interest, can be written ... 

When water is mixed with another liquid, the number of bonds can increase, as, for instance, in water-ethanol solutions (structure formers) or decrease (structure breakers). However, in all cases, the tetrahedral structure vanishes (except, of course, for isotopic mixtures of light and heavy water). As a consequence, the anomalies of liquid water are strongly reduced upon addition of other components. For instance, 7% of ethanol is sufficient to completely suppress the maximum in the temperature dependence of the density of the mixture [9]. 

Adsorption onto activated charcoal (Norit A) has been used for small oligonucleotides, up to tetranucleotides (Crane and Lipman 1953 Mandeles and Kammen 1966). The method is quicker and more convenient than DEAE-cellulose chromatography. Mandeles and Kammen (1966) used Norit A suspended in 1 mM phosphate 1 mM pyrophosphate buffer at pH 6.0 at a concentration of 100 mg/ml. The nucleotide solution is adjusted to pH 3 and 5 mg Norit for every optical density unit ( 40 pg) of nucleotides is added. The charcoal is collected on a filter paper and washed with water. (A good quantitative measure of or radio-activity may be obtained by counting the dry filter paper in a Geiger-Muller thin window counter.) The nucleotide material is eluted with a small volume of a mixture of ethanol, water and ammonia (600 400 6.5 v/v/v) which is then removed by drying under reduced pressure at 40°C. 

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