Solubility molecule size

Small molecule size-c Ecluslon chrmutography 441 Soap-film meter (GC) 4, 235 Solid-phase extraction 777 cartridges 777 membranes 780 optimization 777, 783 sorbents 778, 785 trace enrichment 777, 783 Solubility parameters 460 Solvatochromic parameters GC 191... 

You have taken a close look at the attractive forces between solute and solvent particles. Now that you understand why solutes dissolve, it is time to examine the three factors that affect solubility molecule size, temperature, and pressure. Notice that these three factors are similar to the factors that affect the rate of dissolving. Be careful not to confuse them. 

Since the methacrylic acid molecules are soluble in both styrene and water, it is important to determine the efficiency of its incorporation in the copolymer latexes. Figure 29 is an H-NMR spectrum of the copolymer latexes. The NMR peak areas of the phenyl (at 6.2-7.4 ppm) and methyl (at about 0.5 ppm) protons allow one to calculate the composition of copolymer latexes. Table 5 lists the compositions and sizes of the copolymer latexes obtained. The efficiency is quite high and increases with increasing amount of methacrylic acid. 

On the basis of interaction between the particles or macromolecules of the dispersed phase with the molecules of the dispersion medium, colloidal systems are classified into three groups 1) lyophilic, solvent loving colloids, in which the disperse phase is dissolved in the continuous phase 2) lyophobic, solvent hating colloids, in which the disperse phase is insoluble in the continuous phase and 3) association colloids, in which the dispersed phase molecules are soluble in the continuous phase and spontaneously self-assemble or associate to form aggregates in the colloidal size range. 

Association colloids are aggregates or associations of amphipathic surface active molecules. These molecules are soluble in the solvent, and their molecular dimensions are below the colloidal size range. When present in solution at concentrations above a certain critical value (the critical micelle concentration), these molecules tend to form association colloids (micelles) (Fig. 1). 

Elliott and Lira show that ajb 8, where d is the solubility parameter. For large molecules, the solubility parameter varies little with respect to molecular weight. Thus, increases in C correspond primarily to increases in cohesive energy density, not molecular size. Taking pentane as an example of component 1, we can estimate ( from solubility parameters to be 0.16, 0.27, 0.33, 0.40, 0.52, 0.62, 0.84 for cyclohexane, benzene, acetone, n-hexanol, ethanol, methanol, and water. This provides an idea of the range of chemical functionalities addressed in Fig. 4. 

De Haan, H. (1972a). Molecule-size distribution of soluble humic compounds from different natural water. Freshwater Biol. 2, 235-241. 

Many groups have investigated the suitability of various solvents for use in LM systems and have attempted to describe the relationship between solvent characteristics and transport properties [93-96]. Of all solvent properties, dielectric constant seems to be most predictable in its effect on transport [92]. For solvents, such as the halocarbons, transport usually decreases with increasing dielectric constants [93]. Figure 2.10 shows this trend for alkali metals binding by dicyclohexano-18-crown-6 in a number of alcohols. This trend holds true for many simple systems, but it breaks down under more complex conditions. Solvent donor number, molecule size, solvent viscosity, carrier solubility in the solvent, permanent and induced dipole moments, and heats of vaporization are important [94]. 

In this section we will restrict our discussion to small polar (oihwater partition coefficient A eUier 0.003) nonelectrolytes. However, before discussing this question in detail, it is worth noting that the value of the permeability coefficient of membranes for a large lipophilic molecule is determined by the molecule lipid solubility, its chemical nature, its molecule size and shape, and the number of hydrogen bonds (TVh) form with water. The permeability coefficient... 

The solubilities of small molecules in fluorous solvents are determined to a large extent by two parameters solute polarity and size. The first is an extension of the like dissolves like paradigm. The second is uniquely important to perflu-orinated solvents because of low intermolecular forces they have large cavities (free volumes) that can accommodate small molecules. The solubilities of gases in fluorocarbons are also well established and show a correlation with the isothermal compressibility of the solvent, supporting the cavity-based solubility model. 

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