Water-acetone binary mixture

Among several dynamic properties of this aqueous mixture, simulations found a striking anomalous concentration region where the self-diffusion coefficient and the orientational relaxation times of water and acetone molecules deviate from their ideal behavior. The diffusion coefficient of water shows a minimum = 0.75 and 

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M. Katayama, and K. Ozutsumi, The number of water-water hydrogen bonds in water tetrahydrofuran and water-acetone binary mixtures determined by means of X-ray scattering, Journal of Solution Chemistry, 37 (6), 841-856,2008. 

In 1910 Serkov (15) determined the conductance of several salts (including lithium bromide) at 25°C in water, methanol, ethanol, acetone, and binary mixtures of these solvents, reporting a value of 144 12 1 cm2 eq-1 for Ao for lithium bromide in acetone. He found that, unlike the other mixtures, acetone solutions exhibit no parallelism between conductance and fluidity, and concluded that when the surveyed ionophores are dissolved in acetone, the complexity of the solvates formed increases as Aq for the ionophores decreases. 

Note that these single ion values were obtained from entirely different extrathermodynamic assumptions elaborate extrapolation procedure in the case of the water-acetone mixtures, and tetraphenylboron assumption for the water-THF mixture. n-Bu4N+ and Br showed similar behavior in the two binary systems studied this might be the consequence of the similarity between the thermodynamic properties of the two aqueous binaries e.g., both are typically aqueous systems with AHE < T ASE. ... 

Figure 5.2.3 depicts the HPLC chromatogram of a tomato peel extract monitored by UV absorbance at 469 nm. The separation was performed on a 150 x 4.6 mm C30 column (ProntoSil, 3 xm, 200 A, Bischoff, Germany) at room temperature and a flow rate of 1 ml/min with a binary mixture of acetone/ water, developed for LC-NMR experiments. The 50-min gradient elution was performed in four steps, i.e. (1) an initial 3 min with 75/25 (v/v) acetone/water, (2) a 24-min gradient to 100% acetone, (3) an isocratic step from 27 45 min with 100% acetone, and (4) a 2-min gradient back to the initial conditions. 

The behavior of the Fick diffusion coefficient in nonideal systems may be complicated, while the Maxwell-Stefan diffusion coefficients behave quite well, and are always positive for binary systems. In nonideal binary systems, the Fick diffusivity varies with concentration. As seen in Figure 6.1, water-acetone and water-ethanol systems exhibit a minimum diffusivity at intermediate concentrations. Table 6.1 displays the dependency of binary diffusivity coefficients on concentration for selected alkenes in chloroform at 30°C and 1 atm. As the nonideality increases, mixture may split into two liquid phases at certain composition and temperature. 

Figure 6.1. Concentration dependence of the Fick diffusivity for the binary mixtures (a) water (A)—acetone (B) at 45°C, (b) water (A)—ethanol (B) at 40°C in terms of water mole fraction (Tyn and Calus, 1975).

In Fig. 17 we show [292] a partition of Zn between the surface and bulk phase in binary mixtures of H2O with methanol (curve 1) and H2O with acetone (curve 2). Both curves exhibit a deeper minimum for acetone which is more strongly adsorbed on the surface of a mercury electrode than methanol and whose dielectric permittivity is more different from that of water. 

The static mode uses both organic solvents such as toluene [27], methanol [28] or acetone [29] and solvent mixtures (usually in a 1 1 ratio) including dichloromethane-acetone [20,28], acetone-hexane [30,31], heptane-acetone [31], acetone-isohexane [32] or methanol-water [33], The use of mixed solvents as extractants provides improved extraction in terms of expeditiousness and recovery [20,28,30-35] as a result of the solubility parameter for a binary mixture being roughly proportional volumewise to the parameters of its components [36], Thus, in the extraction of Irganox 1010 from polypropylene, the addition of 20% of cyclohexane to 2-propanol doubles the extraction... 

The mobile phase used in the lipophilicity measurements by RP-TLC is usually a binary mixture between an organic solvent and water. The organic solvent can be methanol, acetonitrile, or acetone. The first two can also be used in reversed-phase high-performance liquid chromatography (RP-HPLC) measurements, but... 

The results for the acetone and water system are similar. In Figure 3.5.5 we present the results of correlating VLE data for this binary mixture at 298 K. The use of the... 

In the remainder of this section we examine several EOS-G models using three prototype binary mixtures that form sti ongly nonideal solutions. For comparison, we also include the predictions of the UNIFAC model used directly in the y-(p method wherever applicable. The systems considered are the methanol and benzene (Butcher and Medani 1968), the acetone and water (Gmehling and Onken 1977), and the 2-propanol and water (Barr-David and Dodge 1959) binary mixtures. Note that there are many systems with small to moderate solution nonideality for which all or most of the methods mentioned above work reasonably well. We are not concerned with such systems here because the method selection would not be a problem in such cases. Rather we consider only those systems that are more nonideal and for which the differences between the models discussed here are clearly evident. 

Figure 6.2.1. Excess Gibbs free energy and excess enthalpy of the acetone and water binary mixture at 293 K. The excess Gibbs free energy was calculated from VLE data as described in Section 5.1, The excess enthalpy data are as reported in the DECHEMA Chemistry Data Series Heat of Mixing Collection, Christiansen et al. 19S4, Vol, l,Pt. lb, pp. 148-9.

These binary interaction parameters were obtained using the program WS.EXE described in Appendix. D.5, and the data files am200.dat, mw250.dat, and aw250.dat for acetone-methanol, methanol-water, and acetone-water binary mixtures, respectively.)... 

Acrylonitrile, styrene, and isobutylene were irradiated at low temperatures in binary mixtures with either low molecular weight compounds or polymers. The reagents were mixed at room temperature, sealed under vacuum, and the resulting liquid or swollen polymer was rapidly cooled to the irradiation temperature. Irradiations were carried out with cobalt-60 gamma-rays at a dose rate of 2000 rads/min. After irradiation the samples were warmed to room temperature under two different standard conditions. The sealed ampoules were either immersed in a water bath at 25 °C. immediately after irradiation or first opened at —196°C. and then stirred in a large excess of warm acetone. The polymer was separated and dried to constant weight. 

Figure 10.3-9 Vapor-liquid equilibria of the acetone -f water binary mixture correlated using the combination of the Peng-Robinson equation of state, the Wong-Sandler mixing rule, and the NRTL activity coefficient model. The three parameters in this model have been fit to data for each isotherm.

Figure 10.3-13 Vapor-liquid equilibria of the acetone-water binary mixture described by the Peng-Robinson equation of state and the van der Waals one-fluid mixing rules. The solid lines result from the value of the binary parameter xy being fit to the data at 298 K. The dotted lines are the highly nonideal (and unrealistic) behavior predicted by setting k j = 0.

In this section we have considered liquid-liquid equilibrium in binary mixtures, and in ternary mixtures in which there was limited mutual solubOity between only one pair of components (for example, the methyl isobutyl ketone + water binary mixture in the methyl isobutyl ketone + water + acetone system). In fact, liquid-liquid equilibria can be more complicated than this when two of three binary pairs in a ternary-mixture, or all three of the binary pairs, have limited solubility. Such systems can be described by... 

Standard curves for each binary mixture have to be prepared at a given temperature. Some examples of binary systems that can be analyzed are hexane-benzene and acetone-water, as well as various lower-molecular-weight alcohols in water. 

Interestingly, mostly those aqueous binary mixtures that contain a marked amphiphilic character towards water are found to be particularly important in chemistry and biology. This is clearly manifest in all useful aqueous binary mixtures such as DMSO, methanol, ethanol, TBA, acetone, and dioxane to name a few. Some of these solvents (DMSO, EtOH) are used at high concentration as effective denatur-ants of protein. At low concentration they can exhibit a reversal of role and serve as a promoter of stability. In this low-concentration regime the binary mixtures also promote the catalytic activity of enzymes, as discussed above. Recent experimental, theoretical, and simulation results exhibit the phase-transihon-hke scenarios discussed in this chapter. These systems need to be studied in great detail as much remains to be understood. 

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