Chloroform, partial pressure

The chloroform/polystyrene solution exhibits highly nonideal behavior. As shown by curve C in Figure 4, the x parameter for this solution rises from a low value to a high value as solvent concentration increases. However, as shown in Figure 5, the partial pressure of chloroform above a mixture of... 

The curves in Fig. 10 were drawn for the particular instance of a volatile solute dissolved in a volatile solvent, such as would exist for the acetone-chloroform system (whose diagram is very nearly like that of Fig. 10B). For many nonvolatile solutes, it not possible to trace smooth partial pressure curves across the entire range of mole fractions. This is especially true for aqueous salt solutions, where at a certain concentration of solute the solution becomes saturated. Any further addition of crystalline solute to the system does not change the mole fraction in the liquid phase, and the partial pressure of water thereafter remains constant, in accord with the phase rule. This phenomenon permits the use of saturated salt solutions as media to establish fixed relative humidity values in closed systems [12],... 

By assuming the solution to be ideal, apply Raoult s Law to calculate the partial pressures of acetone and chloroform. 

When AsIkT = 0, such as in a mixture of pentane and hexane, Raoult s law for partial pressure will apply precisely. When As /kT > 0, the 1—2 hetero-bonds are weaker than the average of the 1 — 1 and the 2—2 homo-bonds, such as between water and acetone, and we have a positive deviation to elevate the partial pressure. When Ae/kT < 0, the 1—2 bonds are stronger, such as between acetone and chloroform, and we have a negative deviation to depress the partial pressure. The value of P2 versus X2 for a range of values of E/RT is given in figure 5.16. 

The increase of the solvent concentration in SB41 films on raising the partial pressure of chloroform vapor, and the related loss of long-range order, can be explained in terms of the so-called dilution approximation for the bulk block copolymer phases [167, 168], The above results clearly demonstrate the high sensitivity of the polymer-polymer interactions towards solvent content. Therefore, the microphase-separated structures in swollen block copolymer films can be used as a qualitative measure of the degree of swelling of the films [49, 166],... 

Example 1. Partial pressures of chloroform and acetone solutions (in torr at 35.2°C) above a solution of these components are given below. Calculate the Raoult s law reference activity coefficients for each component at each composition. 

It is difficult to draw tangent lines to partial pressure curves for estimating Henry s law constant with accuracy. Show that an alternative way of obtaining the Henry s law constant is as Kt = lim, 0 yi(RL)Pi. From the data for the acetone-chloroform system given in Example 1, evaluate KAc and Kchl. and compare the values obtained with those determined by drawing tangent lines. 

Fig. 21.2. Typical BET isotherm with specific analyte incorporation within the linear slope of the adsorption curve number of moles chloroform n in a QCM layer as a function of the partial pressure p.

Specific effects on spectroscopy and photophysics induced by complexation of the D-A chromophores with various solvent molecules have been examined for all the compounds under consideration. The idea of the beam work is to generate n solute-solvent complexes and to determine thereby the relation between the solute-solvent interactions and the excited-state CT process. Kajimoto et al. [81a,c, 89], Phillips and co-workers [82], Peng et al. [83], Bernstein and co-workers [84] and others [85, 88, 90-92] have shown that solute-solvent complexes of CDMA were readily produced by varying the partial pressure of the compounds and the stagnation pressure of the carrier gas. Cyclohexane, chloroform, carbon tetrachloride, methyl fluoride, trifluoromethane, dichloromethane, acetone, acetonitrile, metha-... 

The effects of the mixed supersonic expansion of CDMA with various solvent molecules (such as cyclohexane, carbon tetrachloride, acetone, acetonitrile, methanol, dichloromethane and chloroform) on the emission spectra have been investigated by Phillips and co-workers [82d[. The cluster size distribution was varied by changing the nozzle temperature and the partial pressure of the solvent. Two emission components were observed in each case. The long-wave emission was attributed to dimers (which can be isolated or solvated) and to monomer complexed with chloroform or dichloromethane (of unknown stoichiometry). On the other hand, it has been reported by Bernstein and co-workers [84] that CDMA forms with acetonitrile two kinds of 1 1 complexes of different geometry. The first cluster has a structured excitation spectrum, similar to that of the bare molecule, but blue shifted by about 252 cm . The second exhibits a broad excitation spectrum with some resolvable features between 31400 and 31 600 cm (Table 2). The complexes show different fluorescence spectra excitation into the broad absorption leads to the red-shifted emission with respect to that of the monomer (Figure 8) and of the blue ... 

Figure 2.9 shows the plot of the partial pressure of chloroform in an oleyl alcohol-chloroform mixture as a function of the percentage of chloroform in the gas phase. Significant deparmres from Raoult s law are apparent when the amount of dissolved chloroform exceeds about 20%. 

Fig. 21.11. Partial pressures calculated from the total pressure curve by Boissonnas method (points) compared with observed partial pressures (full lines) for the system ethanol (1) + chloroform (2) at 45 °C.

Using Raoult s Law, predict the partial pressures in the vapor above a solution containing 0.250 mol acetone (P = 345 torr) and 0.300 mol chloroform (PO = 295 torr). 

Use the following vapor pressure diagram to estimate (a) the partial pressure of chloroform, (b) the partial pressure of acetone, and (c) the total vapor pressure of a solution in which the mole fraction of CHCI3 is 0.30, assuming ideal behavior. 

For a given concentration of VCKH in the oil phase, the partial pressure of the VOC is lower by a factCM of D relative to the water case. For example, 1 ppm of chloroform... 

As shown in Table n, chloroform and carbon tetrachloride have about the same Henry s Law constant above oil, even though carbon tetrachloride is considerably more volatile above water than chloroform. The high distribution coefficient for carbon tetrachloride significantly reduces the Henry s Law constant for the oil phase. The relatively high partial pressure of tetrachloroethylene above water is significantly reduced in oil due to the large distribution coefficient... 

In an idealized stripping-gas case, only the VOCs are in the gas phase and should condense since the solvent is consider nonvolatile compared to the VOCs. For a 100 ppm chloroform concentration in sunflower oil at 20°C, the partial pressure of the... 

The Henry s law constant for chloroform in acetone at 35.17 °C is 0.199 if the vapor pressure is in atm, and concentration of chloroform is in mole fraction. The partial pressure of chloroform at several values of mole fraction is ... 

Since the majority of flames which have been studied are open to the atmosphere, it is convenient to specify concentrations as partial pressures in atm, i.e. as mol fractions. In the unbumt gas there will be fuel, oxidant and diluent for example, a hydrogen flame at 2200 K might be fed with 0-400 atm Hg, 0-139 atm O2 and 0-460 atm of Ng. If any substance is added to the flame, these quantities will be altered—in one experiment to study the effect of chlorine on potassium a portion of the nitrogen was saturated with chloroform vapour to produce a partial pressure of 0-008 atm, while a further portion carried a spray of 0-2 M potassium chloride solution in to the flame, producing a partial pressure of 7 x 10 atm ofpotassiiun and 0-018 atm of water. The resulting composition of the unbumt gas will therefore be ... 

Dinitrogen pentoxide (N2O5) decomposes in chloroform as a solvent to yield NO2 and O2. The decomposition is first order with a rate constant at 45 °C of 1.0 X 10 s. Calculate the partial pressure of O2 produced from 1.00 L of 0.600 M N2O5 solution at 45 °C over a period of 20.0 hr if the gas is collected in a 10.0-L container. (Assume that the products do not dissolve in chloroform.)... 

In the right column the mixture nitric acid/water is shown. For this the explanations given for the mixture acetone/chloroform hold as principal. Taking into account that there are extremely strong interaction energies between nitric acid and water molecules the described effects are very distinct in this case. There are, for example, very negative deviations from Raoult s law and the distance of the equilibrium curve to the diagonal is considerable. Solutions of small amounts of nitric acid in water show very small partial pressures of the nitric acid. This effect is even more... 

Depending on the affinity of a gas or vapor for blood, the transfer firom the alveoli to the eapillaries may be diffusion-limited or perfusion-limited. The differenee ean be illustrated by examining two solvents, styrene and methyl ehloroform. Beeause of the high solubility of styrene (X=52) large amounts of it can be taken up by the blood, and the transfer is only diffiision-limited. On the other hand, methyl chloroform is not very soluble (A,=l. 4) and its partial pressure rises rapidly to that of the alveolar air, at which point no net transfer takes place. The amount of methyl chloroform taken up by the blood will depend exclusively on the amount of available blood flow and not on the diffusion properties of the gas-blood interface. This kind of transfer is perfusion-limited. 

Fig. 3.6. Partial pressures (o), activities (6), and activity coefficients (c) for the system acetone-chloroform at 35.17 C. [Data of Zawidzki, Z. Physik. Chem. 35,129 (1900).] Activity coefficients fitted by three-suffix Margules equations Aab log 0.39, Aba log 0.51...

Fig. 27. Partial pressures in the mixture acetone-chloroform at 35.2 0. (Note the azeotrope.)...

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