INDEX acid-water

The permeation and separation characteristics of PVA-g-AN membranes toward acetic acid-water mixtures were expressed as permeation rate (flux) (0, separation factor (a) and pervaporation separation index (PSI). 

Recent studies have made it possible to classify water-organic solvent systems in CCC for separation of organic substances on the basis of the liquid-phase density difference, the solvent polarity, and other parameters from the point of view of stationary-phase retention in a CCC column [1,3-9]. Ito [1] classified some liquid systems as hydrophobic (such as heptane-water or chloroform-water), intermediate (chloroform-acetic acid-water and n-butanol-water) and hydrophilic (such as n-butanol-acetic acid-water) according to the hydrophobicity of the nonaqueous phase. Thirteen two-phase solvent systems were evaluated for relative polarity by using Reichardt s dye to measure solvachromatic shifts and using the solubility of index compounds [6]. 

When the overall oxidation state of a system is desired, unless a water is obviously anaerobic (e.g., it has an H2S odor) one should first attempt to measure dissolved oxygen as an index of system redox state. Eh measurements are unlikely to be stable and thermodynamically meaningful in surface-waters, except in acid waters (where ferrous and ferric species are usually present). Eh measurements may be stable and meaningful in anaerobic sediments or groundwaters, when species of iron, sulfur, and manganese dominate the redox chemistry, but otherwise are of qualitative value only. 

Figure 12. Solid curve the refractive index of water showing a simple, monotonic dispersion curve. Dotted curve the contribution of the 189 nm band of iV-methylacetamide at a 1 M concentration added on to the water curve using equation 19. The point to be made is that there is no way to match the background curve of a good solvent to the anomalous dispersion of a chromophoric system under study. Such matching is commonly attempted to remove light scattering problems which depend on the difference in refractive index of the particle, n, with that of the solvent, n, i.e., (tip—nf). The dashed curve adds the second dispersion term in equation 25. Also included is the calculated refractive index of particulate poly-L-glutamic acid (PGA) (see section 4(cKii))-...

Hydrochloric acid is able to react with a hydroxyl-free silica surface without a barrier, with formation of hydroxyl groups and weakly bonded chlorine (Fig. 5( 1)). The distance between chlorine and silicon for the system under study is 2.417 A, compared to the experimental value of 2.017 A and calculated value 2.054 A for SiCU. The formal charge on chlorine for the system under study is -0.754 e, compared with -0.354 e for SiCU- The Wiberg index (bond order) for the chlorine-silicon bond for the system under study is 0.3231, compared to a value of 0.8468 for SiCU- A similar phenomenon is presented for systems like water and hydrochloric acid/water (Fig. 5(2)). These data show that the chlorine atom is bonded to the silica cluster mainly as an ion, and it is possible to understand the system under study as an ion-pair, which may dissociate into ions. As a result the chatted particles will be repelled electrostatically. 

FIGURE 25 Competitive adsorption of alcohols and water on crystalline silicic acids, (a) Methanol (index l)/water (2) on H2Si2o04i 3.6 H2O (b) propanol (l)/water (2) on H2Si2o04i 5.2H2O. w f"Vra specific reduced surface excess of alcohol, Xi molar fraction of alcohol in the equilibrium solution. (From Ref. 159.)... 

Dichloroacetic acid [79-43-6] (CI2CHCOOH), mol wt 128.94, C2H2CI2O2, is a reactive intermediate in organic synthesis. Physical properties are mp 13.9°C, bp 194°C, density 1.5634 g/mL, and refractive index 1.4658, both at 20°C. The Hquid is totally miscible in water, ethyl alcohol, and ether. Dichloroacetic acid K = 5.14 X 10 ) is a stronger acid than chloroacetic acid. Most chemical reactions are similar to those of chloroacetic acid, although both chlorine... 

Chloroacetyl chloride [79-04-9] (CICH2COCI) is the corresponding acid chloride of chloroacetic acid (see Acetyl chloride). Physical properties include mol wt 112.94, C2H2CI2O, mp —21.8 C, bp 106°C, vapor pressure 3.3 kPa (25 mm Hg) at 25°C, 12 kPa (90 mm Hg) at 50°C, and density 1.4202 g/mL and refractive index 1.4530, both at 20°C. Chloroacetyl chloride has a sharp, pungent, irritating odor. It is miscible with acetone and bensene and is initially insoluble in water. A slow reaction at the water—chloroactyl chloride interface, however, produces chloroacetic acid. When sufficient acid is formed to solubilize the two phases, a violent reaction forming chloroacetic acid and HCl occurs. 

Methylene iodide [75-11-6], CH2I2, also known as diio dome thane, mol wt 267.87, 94.76% I, mp 6.0°C, and bp 181°C, is a very heavy colorless Hquid. It has a density of 3.325 g/mL at 20°C and a refractive index of 1.7538 at 4°C. It darkens in contact with air, moisture, and light. Its solubiHty in water is 1.42 g/100 g H2O at 20°C it is soluble in alcohol, chloroform, ben2ene, and ether. Methylene iodide is prepared by reaction of sodium arsenite and iodoform with sodium hydroxide reaction of iodine, sodium ethoxide, and hydroiodic acid on iodoform the oxidation of iodoacetic acid with potassium persulfate and by reaction of potassium iodide and methylene chloride (124,125). Diiodoform is used for determining the density and refractive index of minerals. It is also used as a starting material in the manufacture of x-ray contrast media and other synthetic pharmaceuticals (qv). 

The mineral talc is extremely soft (Mohs hardness = 1), has good sHp, a density of 2.7 to 2.8 g/cm, and a refractive index of 1.58. It is relatively inert and nonreactive with conventional acids and bases. It is soluble in hydroduoric acid. Although it has a pH in water of 9.0 to 9.5, talc has Lewis acid sites on its surface and at elevated temperatures is a mild catalyst for oxidation, depolymerization, and cross-linking of polymers. 

The reaction mixture is heated and allowed to reflux, under atmospheric pressure at about 100°C. At this stage valve A is open and valve B is closed. Because the reaction is strongly exothermic initially it may be necessary to use cooling water in the jacket at this stage. The condensation reaction will take a number of hours, e.g. 2-4 hours, since under the acidic conditions the formation of phenol-alcohols is rather slow. When the resin separates from the aqueous phase and the resin reaches the requisite degree of condensation, as indicated by refractive index measurements, the valves are changed over (i.e. valve A is closed and valve B opened) and water present is distilled off. 

Bromine (128 g., 0.80 mole) is added dropwise to the well-stirred mixture over a period of 40 minutes (Note 4). After all the bromine has been added, the molten mixture is stirred at 80-85° on a steam bath for 1 hour, or until it solidifies if that happens first (Note 5). The complex is added in portions to a well-stirred mixture of 1.3 1. of cracked ice and 100 ml. of concentrated hydrochloric acid in a 2-1. beaker (Note 6). Part of the cold aqueous layer is added to the reaction flask to decompose whatever part of the reaction mixture remains there, and the resulting mixture is added to the beaker. The dark oil that settles out is extracted from the mixture with four 150-ml. portions of ether. The extracts are combined, washed consecutively with 100 ml. of water and 100 ml. of 5% aqueous sodium bicarbonate solution, dried with anhydrous sodium sulfate, and transferred to a short-necked distillation flask. The ether is removed by distillation at atmospheric pressure, and crude 3-bromo-acetophenone is stripped from a few grams of heavy dark residue by distillation at reduced pressure. The colorless distillate is carefully fractionated in a column 20 cm. long and 1.5 cm. in diameter that is filled with Carborundum or Heli-Pak filling. 4 hc combined middle fractions of constant refractive index are taken as 3-l)romoaccto])lu iu)nc weight, 94 -100 g. (70-75%) l).p. 75 76°/0.5 mm. tif 1.57,38 1.5742 m.]). 7 8° (Notes 7 and 8). 

To a solution of 93.8 g of the monoglycol ester in 500 ml of benzene, there are added 55 g of nicotinic acid chloride and 25 g of trimethylemine dissolved in 200 ml of benzene. The solution is stirred gently at a temperature of 60°C for two hours. After this time, the solution is cooled and washed successively with water, dilute hydrochloric acid, dilute ammonia and water until neutrality, it is dried over anhydrous sodium sulfate, and the sol vent Is evaporated under vacuum In this wey llOg of glycol 2-(p-chlorophenoxy)-2-methylpropionate nico-tlnate Is prepared, which represents a yield of 84%. The product is a sllghly yellow oil having a refraction index of no = 1.5422 and which is distilled with decomposition et 214°C at a pressure of 0.3 mm. 

Domestic heating coil internal corrosion. Where naturally soft or lean city water is supplied and the Langelier Saturation Index (LSI) is below -1.0, acid corrosion takes place as a result of the acidic nature of the water. This water often has a high dissolved gas content, which additionally leads to pinhole corrosion. Where water velocities are too high (say, over 6 ft/s 1.8 m/s) the protective oxide layer is stripped off and erosion corrosion takes place. 

Phosphoric acid ester was used as a model for the estimation of concentration of a reagent in an adsorbed layer by optical measurements of the intensity of a beam reflecting externally from the liquid-liquid interface. The refractive index of an adsorbed layer between water and organic solution phases was measured through an external reflection method with a polarized incident laser beam to estimate the concentration of a surfactant at the interface. Variation of the interfacial concentration with the bulk concentration estimated on phosphoric acid ester in heptane and water system from the optical method agreed with the results determined from the interfacial tension measurements... 

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