Ethanol vapour pressure

Solubility Insoluble in water very soluble in diethyl ether and ethanol Vapour pressure 133 Pa at 35.4°C (Lin Bieron, 1993)... 

Subcooled reflux to maintain low ethanol vapour pressure... 

If the pump is a filter pump off a high-pressure water supply, its performance will be limited by the temperature of the water because the vapour pressure of water at 10°, 15°, 20° and 25° is 9.2, 12.8, 17.5 and 23.8 mm Hg respectively. The pressure can be measured with an ordinary manometer. For vacuums in the range lO" mm Hg to 10 mm Hg, rotary mechanical pumps (oil pumps) are used and the pressure can be measured with a Vacustat McLeod type gauge. If still higher vacuums are required, for example for high vacuum sublimations, a mercury diffusion pump is suitable. Such a pump can provide a vacuum up to 10" mm Hg. For better efficiencies, the pump can be backed up by a mechanical pump. In all cases, the mercury pump is connected to the distillation apparatus through several traps to remove mercury vapours. These traps may operate by chemical action, for example the use of sodium hydroxide pellets to react with acids, or by condensation, in which case empty tubes cooled in solid carbon dioxide-ethanol or liquid nitrogen (contained in wide-mouthed Dewar flasks) are used. 

R. C. Pemberton and C. J. Mash. "Thermodynamic Properties of Aqueous Non-Electrolyte Mixtures II. Vapour Pressures and Excess Gibbs Energies for Water-)- Ethanol at 303.15 to... 

A differential vapour-pressure technique has been used to determine the molecular weights of phosphonic and phosphinic acids in 95% ethanol. Cryoscopic and n.m.r. studies have been made on solutions of phosphinic acids in sulphuric acid and oleum. Mass spectrometry has indicated the ready formation of phosphinylium ions after electron bombardment of phosphonic and phosphinic acids and their derivatives. However, the cryoscopic results in sulphuric acid indicated that reaction did not proceed beyond protonation, and the n.m.r. study on oleum solutions suggested that sulphonation occurred. 

We recall from Chapter 5 how the intensity of a smell we detect with our nose is proportional to the vapour pressure of the substance causing it. The vapour pressure of ethanol is P(ethanoi), its magnitude being proportional to the mole fraction of ethanol in the brandy brandy typically contains about 40 per cent (by volume) of alcohol. Although adding table salt does not decrease the proportion of the alcohol in the brandy, it does decrease the apparent amount. And because the perceived proportion is lowered, so the vapour pressure drops, and we discern the intensity of the smell has decreased. We are entering the world of perceived concentrations. 

The explanation for the above is twofold. Firstly there is the effect of increasing cavita-tional collapse energy via a lowering in vapour pressure as the temperature is reduced (see above). This does not adequately explain the effect of the change in solvent. The primary process is unlikely to occur inside the cavitation bubbles and a radical pathway should be discarded. The most likely explanation is that the disruption induced by cavitation bubble collapse in the aqueous ethanolic media is able to break the weak intermolecular forces in the solvents. This will alter the solvation of the reactive species present. Significantly the maximum effect is found in 50 % w/w solvent composition - the solvent composition very close to the maximum hydrogen bonded structure. 

Solubility Slightly soluble in water (152 mg/L at 20 °C) (ECETOC, 1986) and chloroform miscible with diethyl ether and ethanol (Lide Milne, 1996) (g) Volatility Vapour pressure, 1.28 kPa at 25 °C (Lide Milne, 1996) relative vapour density (air = 1), 3.7 (Verschueren, 1996) flash-point (closed-cup), 15 °C (Coty et al., 1987)... 

Solubility-. Very slightly soluble in water (0.05% by volume) miscible with benzene, chloroform, diethyl ether, carbon disulfide and ethanol (Budavari, 1996) Vapour pressure 12 kPa at 20°C relative vapour density (air = 1), 5.3 at the boiling-point (American Conference of Governmental Industrial Hygienists, 1991)... 

Determination of pure component parameters. In order to use the EOS to model real substances one needs to obtain pure component below its critical point, a technique suggested by Joffe et al. (18) was used. This involves the matching of chemical potentials of each component in the liquid and the vapour phases at the vapour pressure of the substance. Also, the actual and predicted saturated liquid densities were matched. The set of equations so obtained was solved by the use of a standard Newton s method to yield the pure component parameters. Values of exl and v for ethanol and water at several temperatures are shown in Table 1. In this calculation vH and z were set to 9.75 x 10"6 m3 mole"1 and 10, respectively (1 ). The capability of the lattice EOS to fit pure component VLE was found to be quite insensitive to variations in z (6[Pg.90]

Pemberton R.C., Mash C.J., "Thermodynamic properties of aqueous nonelectrolyte mixtures II. Vapour pressures and excess Gibbs energies for water + ethanol at 303.15 K to 363.15 K determined by an accurate static method"., J. Chem. Therm., 1978, 10, 867-88. 

From Table 3.3 ethanol has a saturated vapour pressure ps of 500mbar at 62 °C ( 60 °C). From Equation (3.4) ... 

Raoult s Law applies to certain liquid mixtures which are discussed in fuller detail in Frame 34. Two liquids, referred to as binary liquids, can, in some cases (e.g. ethanol and water), be miscible in all proportions. Figure 33.1 shows two liquids A and B at constant temperature, T, which are present in a binary mixture. Both A and B are assumed, in this case, to be volatile and thus now each liquid will contribute to the overall vapour pressure P. 

If the mixture has a molecule ratio of 90% water and 10% ethanol, (ethanol has a vapour pressure of, say, E) then ... 

Figure 2.3 (a) Plots of vapour pressure versus mole fraction of HFA 227 for propellant systems composed of HFA 134a and HFA 227 at 6, 16, 25 and 42°C showing ideality of mixing (Raoult s law obeyed). (Reproduced from reference 3 with permission.) (b) Plots of vapour pressure of HFA 134a (circles) and HFA 227 (squares) versus mole fraction of ethanol at 21.5°C. Solid symbols represent experimental data open symbols represent theoretical values calculated assuming ideal (Raoult s law) behaviour. (Reproduced from reference 4 with permission.)... 

Ap2=Ap+plAx2 The smaller the value chosen for Ax2, the more precise is the method.t Fig. 21.11 shows the excellent agreement obtained between observed and calculated partial vapour pressures for the system ethanol H- chloroform at 45 °C. 

This technique, developed by Eyraud [140] modified by Katz et al. [143] and recently by Cuperus et al. [141], is based on the controlled blocking of pores by capillary condensation of a vapour (e.g. CCli, methanol, ethanol, cyclohexane), present as a component of a gas mixture, and the simultaneous measurement of the gas flux through the remaining open pores of the membrane. The capillary condensation process is related to the relative vapour pressure by the Kelvin equation. Thus for a cylindrical pore model and during desorption we have... 

Fig. 6.6. The vapour pressures of the components and the total vapour pressure of a liquid mixture that deviates positively from Raoult s Law (schematic). Water-ethanol mixtures deviate from Raoult s Law in this manner.

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