Water potassium dispersion, effect

Colloidal potassium has recently been proved as a more active reducer than the metal that has been conventionally powdered by shaking it in hot octane (Luche et al. 1984, Chou and You 1987, Wang et al. 1994). To prepare colloidal potassium, a piece of this metal in dry toluene or xylene under an argon atmosphere is submitted to ultrasonic irradiation at ca. 10°C. A silvery blue color rapidly develops, and in a few minutes the metal disappears. A common cleaning bath (e.g., Sono-clean, 35 kHz) filled with water and crushed ice can be used. A very fine suspension of potassium is thus obtained, which settles very slowly on standing. The same method did not work in THF (Luche et al. 1984). Ultrasonic waves interact with the metal by their cavitational effects. These effects are closely related to the physical constants of the medium, such as vapor pressure, viscosity, and surface tension (Sehgal et al. 1982). All of these factors have to be taken into account when one chooses a metal to be ultrasonically dispersed in a given solvent. 

An intermediate polymerization technique between emulsion polymerization and suspension polymerization has been described. Here, the monomers are first dispersed in water containing a small amount of surfactant and a high molecular weight alcohol to form very small droplets of monomer. The polymerization is effected with a water-soluble free radical initiator, such as potassium per-oxydisulfate (4). 

Pure benzoic acid is a white powdery crystalline solid (m.p. 122°C) only sparingly soluble in water at normal temperatures. Because of this, it is added to the drink in the soluble form of its sodium or potassium salts. It is normal practice to disperse the benzoate completely during batch makeup before addition of the acid component, with its resulting pH reduction, to avoid localised precipitation of the free benzoic acid due to its solubility having been exceeded (the solubility of benzoic acid = 0.35% m/v at 20°C). It is the free or undissociated form of benzoic acid that exhibits preservative action and hence its use is only effective when low pH values are encountered, ideally below pH 3, at which point the degree of dissociation reduces to below 10%. 

Table 59 presents activation parameters for the decarboxylation of trichloroacetic acid in various basic solvents. Presumably the acid is in the form of its anion in these solvents. The activation parameters fall into a fairly narrow range and the differences presumably represent specific solvation effects. In an acidic solvent, decanoic acid, the activation parameters for the decomposition of potassium trichloroacetate are increased considerably. The values are A/f = 41.4 kcal.mole" and A5 = 27.7 eu . The activation parameters presumably reflect a composite of a prior equilibrium between decanoic acid and the trichloroacetate anion along with decarboxylation of the latter anion. The rate of decarboxylation of sodium nitroacetate is about five times faster in methanol than in water . This effect was attributed to dispersion of the negative charge at the transition state , a process which is more favorable in the less polar methanol solvent. Similarly, the decar-... 

It was mentioned above that for 1 1 electrolytes, the concentration limit for the stability of an electrostatically stabilized dispersion is an ionic strength in the dispersion medium of order I0 M. This concentration is not very high by way of specific examples, we recall that the effective ionic strength of many biological systems is comparable to this (e.g. an isotonic solution of potassium chloride is ca 016 M and sea water has an ionic strength of order 0-6 M). 

Identification Signal (Formula 130) the yellow (Formula 131) with iron powder seems to be more practical than the above-mentioned. Experimental mixtures of iron powder, HC, and potassium chlorate, developed by the Chemical Corps in World War react vigorously with water and may ignite spontaneously if moistened. The color effect is due to dispersion of ferric chloride (FeCl,). 

When the process is carried out according to Method la it may be assumed that the kind of initiating system (water-soluble initiator or redox system) does not have any significant effect on the morphology of hybrid dispersion particles since the polymerisation proceeds mainly on the surface of DPUR particles and monomer droplets and in the micelles of emulsifier. In the case of water-soluble initiator (potassium persulphate) the polymerisation starts in water where the ion-radicals are formed from the monomer molecules dissolved in water. These ion-radicals can diffuse to DPUR particles, monomer droplets and emulsifier micelles. After this happens the system will consist of ... 

The water-soluble initiator commonly used is potassium or sodium persulfate, and the usual recipe for emulsion polymerization is 200 parts by weight of water, 100 parts by weight of the monomer, and 2-5 parts by weight of a suitable emulsifier [1,2]. The monomer should be neither totally soluble nor totally insoluble in the water medium and must form a separate phase. The emulsifier is necessary to ensme that the monomer is dispersed uniformly as in a true emulsion [3-8]. The polymer that is formed from emulsion polymerization is in the form of small particles having an average diameter around 5 pm. The particles form a stable emulsion in water. Their separation can be effected only through the... 

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