Salt curve

The next example, shown in Fig. 4.6a, is the amusing consequence of continually increasing the concentration of background salt (beyond its aqueous solubility—just to make the point) to the shape of log /J/pH profile for acebutolol (whose normal 0.15 M salt curve [362] is indicated by the thick line in Fig. 4.6a). The base-like (cf. Fig. 4.3a) lipophilicity curve shape at low levels of salt can become an acid-like shape (cf. Fig. 4.2a) at high levels of salt An actual example of a dramatic reversal of character is the ionophore monensin, which has a log P (in a background of Na+) 0.5 greater than logP [276,281]. 

Dialkyl tetralins in LAB feedstocks are readily sulphonated and act as hydrotropes. High DAT levels give surfactants with high solubility and low viscosity. This effect is very significant in formulations. For example the salt curve of 15% active H2P LAS with 3% cocodi-ethanolamide (a common thickener and foam stabiliser) can give a maximum viscosity of 600 cPs with a high DAT LAB, but over 1300 cPs with a low DAT LAB. 

Ether sulphates show a strong salt effect - that is an increase in viscosity on addition of salt (or other electrolyte). The response to electrolyte (the salt curve ) can be very different between ether sulphates, even from different suppliers of the same product. Generally, the more soluble the surfactant, the lower the salt response but higher degrees of ethoxylation reduce salt response, as does branching in the alcohol as shown in Figure 4.20. 

Figure 3 shows both profile equations in action in a titration regime. The observed profile is a minimal combination of the neutral base and salt curves. Please note the dramatic decrease of solubility at pH< 2. It is a direct consequence of the common ion effect, the reciprocal dependence on the counterion concentration in Equation (9). 

Figure 5 Theoretical solubility profile (thick line) and its component curves (thin lines) of a compound containing five acidic and three basic g roups. The pK values are 2, 2.7, 4.1, 5.3, 6.6 (acids) and 12.7, 9.9, 8.3 (bases). Thick dot atpH=4 represents reference solubility of 0.006 units. Broad U-shaped curve in the 2.5

A particular viscosity level is then attained through addition of salt, usually sodium chloride (Section II.C.2). Salt increases viscosity up to a point, after which addition of more salt reduces viscosity. Generally, shampoo viscosity is adjusted on the rising portion of the salt curve. 

Fig. 5. The effect of Mg(N03)2 on the char curves from Cr. Curve 1 is Cr signal in presence of 50

Figure 7.13 shows PSDs for several salts typical of the various classes. Curve 1 is a Canadian potash. Curve 2 is an Italian vacuum salt. Curves 3 and 4 are two samples of the same Bahamian solar salt from two different final suppliers. Curve 5 is a typical dissolver-grade rock salt. All distributions depart from true lognormal by the presence of too much fine material. As shown by the uniformity coefficients, the solar salts have the widest PSDs and the vacuum salt the narrowest. Figure 7.14 shows the variation in PSD caused by screening. All three curves are for rock salt from Weeks Island (United States). These are well-screened fractions whose distributions are closer to lognormal. The uniformity coefficients are about 1.5. 

Fig. 4 Electrical potential (ij/, F) as a function of reduced distance (x = distance from the center of the vesicle to the diameter of the aspherical cell containing one micelle/diameter of the cell) from the vesicle center for different amphiphile concentrations in the absence of added salt. Curves A through D correspond to the following amphiphile concentrations (x 10 ) 0.1,1.0,10.0, 100 M, respectively. The corresponding cell diameters (nm) are 428.7,199.0,92.4 and 42.9, respectively. The vesicle diameter was 265 nm and the area per head group was taken as 75 [49]...

Salt Curve. A graphical representation of the viscosity of a system versus salt concentration. This curve can be an important characteristic of formulated systems in which viscosity control is necessary, such as in shampoo formulas. 

Figure 6.4 shows a comparison of oxygen consumption (in 10" dm kg" ) obtained for virgin polypropylene (curve 6) with the much higher oxygen consumption obtained with polyethylene containing increasing amounts of cobalt salts (curves 1-5). 

Flood 3 was an areal flood in which adsorption was much more important than inaccessible pore volume. The breakout curves from this flood are shown in Fig. 5- The areas under these curves are under total salt curve 2.59 PV... 

Fig. VI-6. The force between two crossed cylinders coated with mica and carrying adsorbed bilayers of phosphatidylcholine lipids at 22°C. The solid symbols are for 1.2 mM salt while the open circles are for 10.9 roM salt. The solid curves are the DLVO theoretical calculations. The inset shows the effect of the van der Waals force at small separations the Hamaker constant is estimated from this to be 7 1 x 10 erg. In the absence of salt there is no double-layer force and the adhesive force is -1.0 mN/m. (From Ref. 66.)...

A method for the generation of benzyne involves heating the diazonium salt from o aminobenzoic acid (benzenediazonium 2 carboxylate) Using curved arrows show how this sub stance forms benzyne What two inorganic compounds are formed in this reaction" ... 

Trialkylammonium salts, such as lidocaine hydrochloride, are titrated in an aqueous solution containing a surfactant. The presence of the surfactant increases the trialkylammonium salt s K , giving a titration curve with a more pronounced break. The effect of adding an immiscible organic solvent, such as methylene chloride or toluene, also is demonstrated. 

Data on infrared curves for many nitroparaffins and their sodium salts have been reported (10,85—89). References 87, 90 and 91 give uv spectra. Accurate analysis and positive identification of the components of a mixture of several nitroparaffins can be obtained by mass spectrometry (qv) (92). 

Fig. 12. Salt retention by coUoidal particles. The curved dashed and soHd lines represent the surface of a negatively charged siUca particle. Around this there is a layer of counter sodium cations outside there is a layer in which sulfate anions (Q) are more concentrated than in the bulk solution.

The solubihty—temperature curves for the Na20—B2O2—H2O system are given in Figure 5 (Table 9). The solubiUty curves of the penta- and decahydrates intersect at 60.6—60.8°C, indicating that the decahydrate, when added to a saturated solution above this temperature, dissolves with crystallisa tion of the pentahydrate and the reverse occurs below this temperature. This transition temperature may be lowered in solutions of inorganic salts, eg, 49.3°C in solutions saturated with sodium sulfate and 39.6°C with sodium chloride. Heats of solution for borax have been determined (67,73) and the manufacturer quotes a value of about 283 kJ/kg (67.6 kcal/mol) (33). 

Salt Brines The typical curve of freezing point is shown in Fig. II-IIO. Brine of concentration x (water concentration is I-x) will not solidify at 0°C (freezing temperature for water, point A). When the temperature drops to B, the first ciystal of ice is formed. As the temperature decreases to C, ice ciystals continue to form and their mixture with the brine solution forms the slush. At the point C there will be part ice in the mixture /(/i+L), and liquid (brine) /i/(/i-t-L). At point D there is mixture of mi parts eutectic brine solution Di [concentration mi/(mi-t-mg)], and mo parts of ice [concentration mol m -t- mo)]. Coohng the mixture below D solidifies the entire solution at the eutectic temperature. Eutectic temperature is the lowest temperature that can be reached with no solidification. 

It is known that Selenium catalyzes reaction of some dye reduction by Sulphide. On this basis spectrophotometric and test-techniques for Selenium determination are developed. Inefficient reproducibility and low sensitivity are their deficiencies. In the present work, solid-phase reagent on silica gel modified first with quaternary ammonium salt and then by Indigocarmine was proposed for Selenium(IV) test-determination. Optimal conditions for the Selenium determination by method of fixed concentration were found. The detection limit of Se(IV) is 10 ftg/L = 2 ng/sample). Calibration curve is linear in the range 50-400 ftg/L of Se(IV). The proposed method is successfully applied to the Selenium determination in multivitamins and bioadditions. 

Experimental curves for the angular dependence of the fluorescence intensity from plated or sputtered submonatomic Ni layers (open triangles), layers produced by the evaporation of a Ni salt solution (open circles), and the silicon substrate (filled circles). 

The shape of the equilibrium line, or solubility curve, is important in determining the mode of crystallization to be employed in order to crystallize a particular substance. If the curve is steep, i.e. the substance exhibits a strong temperature dependence of solubility (e.g. many salts and organic substances), then a cooling crystallization might be suitable. But if the metastable zone is wide (e.g. sucrose solutions), addition of seed crystal might be necessary. This can be desirable, particularly if a uniformly sized product is required. If on the other hand, the equilibrium line is relatively flat (e.g. for aqueous common salt... 

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