Molar volume of methanol

The mole fraction of methanol in a 30% methanol/70% water mixture is 0.16 (Eq. 5-34). The molar volume of methanol is 0.0406 L mol 1. Hence, the molar volume of the mixture can be calculated as (Eq. 3-43, note that we assume additivity) ... 

Here z is gas compressibility factor A gas constant <5 empirical coefficient t>LMN molar volume of methanol under normal conditions saturation pressure for methanol vapor determined by Antuan s formula ... 

Find the molar volume of methanol gas at 100 atm and 300 °C using Peng-Robinson (PR) equation of state. Compare its molar volume when you are using Soave-Redlich-Kwong (SRK) equation of state. 

P2.1 Calculate the compressibility factor and the molar volume of methanol vapor at 200 C and 10 bar... 

Macroscopic measurements are unable to provide unambiguous information about molecular structure. Nevertheless, it is interesting to speculate on the implications of the minimum observed for the partial molar volume of methanol. One interpretation is that in a mostly aqueous environment, there is association of methanol molecules, perhaps involving the formation of dimers. 

Now consider a non-ideal mixture of two substances. Once intermolecular interactions become significant, we cannot think in terms of private energies, entropies and volumes. Nevertheless, it turns out we can express the Gibbs function formally, as shown in equation 19, with one serious limitation. We must take into account that u, v and s depend on the composition of the mixture. For instance, the partial molar volume of methanol in aqueous solution is 38 mL at a mole fraction of 0.2, and 39 mb at a mole fraction of 0.4. 

Fig. 4.24 Heat of immersion of a carbon (prepared by pyrolysis of Saran Polymer A) in different liquids at 300 K. The liquids for points 1-6 were (I) methanol (2) benzene (3) n-hexane (4) 3-methyl benzene (5) 2,2-dimethyl butane (6) 2,2,4-trimethyl pentane. The abscissae represent the molar volumes of the liquids. (Redrawn from the original diagram of Barton, Beswick and Harrison. " )...

If the volume fraction of methanol in the original mixture was (a), then the volume fraction of water would be (1-a). The molar volume of a substance is the ratio of the molecular weight to the density and thus the molar concentration of methanol and... 

For iodine in methanol solution, the partial molar volume of the solute is essentially constant, independent of concentration, and is equal to 62.3 cm ... 

Comelli, F. and Francesconi, R. Isothermal vapor-liquid equilibria measurements, excess molar enthalpies, and excess molar volumes of dimethyl carbonate + methanol. + ethanol, and propan-l -ol at 313.15 K. J. Chem. Eng. Data, 42(4) 705-709, 1997. 

The excess molar volumes of 10-40 mol % methanol/C02 mixtures at 26°C as a function of pressure has been determined. The excess molar volumes varied with composition and pressure significant interaction between CO2 and methanol was noted from the observed excess molar volumes. To better characterize the interaction and its effect on analyte solubility, the partial molar volume of naphthalene at infinite dilution in liquid 10 and 40 mol % methanol/C02 mixtures was determined. The variation of the partial molar volume at infinite dilution with pressure correlated well with isothermal compressibility of the methanol/C02 mixtures (Souvignet and Olesik, 1995). 

The actual molar volumes of the binary solution methanol(l)/water 2) at 2S°C and 1 bar are shown in Fig. 13.3. In addition the values of V, and V2 are plotted as functions of x,. The line drawn tangent to the V-vs.-x, curve at x, = 03 illustrates the procedure by which values of and V2 are obtained. The particular numerical values shown on the graph are those given with Example 11.2. 

Example 1U The need arises in a laboratory for 2,000 cm3 of an antifreeze solution consisting of a 30 mole percent solution of methanol in water. What volumes of pure methanol and of pure water at 25°C must be mixed to form the 2,000 cm3 of antifreeze, also at 2S°C Partial molar volumes for methanol and water in a 30 mole percent methanol solution at 25°C are ... 

Here Vi is the molar volume of the solute / incm3/(mol) at its normal boiling point (for some values of Vu see Tables 2.9a and b), p the viscosity of solvent in pP, i//. an association parameter for solvent, and T the absolute temperature in K. Recommended values of the association parameters are 2.6 for water, 1.9 for methanol, 1.5 for ethanol, and l.Ofor benzene, ether, heptane, and other unassociated solvents. Equation (2.82) should be used only for dilute nondissociating solutions. 

After the separation of carbonyl dinitrophenylhydrazones into classes or into polar and non-polar fractions, the samples can be re-dissolved in a small volume of methanol and the amount present calculated approximately from the absorbance maxima at 365-370 nm using an average molar absorption coefficient of 26000 (Esterbauer, 1982). Alternatively, the amount of carbonyls within individual classes can be calculated from the molar absorptivities shown in Table 5.1. 

From the solubilities in the individual constituents of the solvent and their molar volumes. The molar volume of a ternary mixed solvent (W) in Equation 23 can be obtained from the molar volumes of water, methanol and 1-propanol as an ideal molar volume... 

From the experimental solubilities in binary solvents and molar volumes of the individual constituents. The calculation procedure is the same as above, with the exception that the solubilities of naphthalene in the binary subsystems 1 and 11 were obtained from experiment. The calculation of the solubilities in binary aqueous solvents was described in detail in previous sections. It should be noted that the water/ methanol/ 1-butanol mixed solventand the binary subsystem water/1-butanol are not completely miscible. Only the homogeneous regions of mixed solvents were considered in this paper. 

Quaternary Mixed Solvent. The solubilities of naphthalene in the water/methanol/l-propanol/l-butanol solvent mixture are predicted using Equation 23. The molar volume of an ideal quaternary mixed solvent was calculated as... 

Fig. 1.2 Plots of the molar volume of aqueous solutions of acetonitrile (AcN) and methanol (MeOH) against their mole fraction in solution.

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