Precipitate formation compounds

It is possible to observe effects of organotin(lV) compounds exposure such as inhibition of cleavage of fertilized eggs, interference with the formation of the mitotic spindle, damages affecting chromosome structure, and electron-dense precipitate formation in organelles. 

Kinetic solubility This pragmatic approach starts with a concentrated compound solution in pure DM SO further diluted in a buffer medium. The amount of compound in solution is measured after a few minutes incubation either by recording its UV absorbance (with or without a chromatographic step) or precipitate formation using an optical method (turbidimetry, nephelometry or flow cytometry). This approach mimics the typical path of the compound in biochemical, cellular assays or in vivo animal models. Kinetic solubility usually serves as a quality filter prior to cell based assays (see paragraphs on solubility, permeability and cellular assays). 

Fluoride is a natural component of most types of soil, in which it is mainly bound in complexes and not readily leached. The major source of free fluoride ion in soil is the weathering and dissolution of fluoride rich rock that depends on the natural solubility of the fluoride compound in question, pH, and the presence of other minerals and compounds and of water. The major parameters that control fluoride fixation in soil through adsorption, anion exchange, precipitation, formation of mixed solids and complexes are aluminium, calcium, iron, pH, organic matter and clay [19,20]. 

Formation of mineral deposits occurs through geochemical reactions which often concentrate and precipitate specific compounds quite locally and separately fc un others of sufficiently different chemical properties. In such cases, natural processes do much of the work of concentration and separation for us. If, however, the elements of interest have closely similar chemistries,... 

R. A. Pacer, "Will a precipitate form Will it dissolve " J. Chem. Educ., Vol. 71,1994,69. Principles of ionic compound precipitate formation are shown in a series of four colorful demonstrations (1) Yellow Pbl2 is formed only when Q > Ksp. (2) Upon addition of aqueous ammonia, green NiC03(s) is dissolved due to the formation of the blue complex ion [Ni(NH3)6]2+. 

Coprecipitation is a phenomenon in which otherwise soluble compounds are removed from solution during precipitate formation. It is important to understand that contamination of a precipitate by a second substance whose solubility product has been exceeded does not constitute coprecipitation. 

The formation of hydrotalcite-like phase is confirmed by the XRD investigation. As shown in for the anion rich sample CR, the broad diffraction peaks are indeed characteristics of hydrotalcite-like compounds [36-38]. In the spectrum of CS, however, this hydrotalcite feature is not observable only pronounced brucite-like compound diffractions can be seen. This observation is consistent with the low anion content found in the elemental analysis. The presence of hydrotalcite-like phase in the CR samples indicates the formation of the trivalent cation (Co ) due to the presence of air atmosphere during precipitate formation [39]. 

A small but important class of atmospheric aerosol particles are the ice nuclei. These nuclei promote the freezing of water drops in clouds (see Fletcher, 1962). In this way they play a definite role in the formation of precipitation in mixed clouds containing both water drops and ice crystals. This kind of precipitation formation is due to the fact that the saturation vapour pressure over ice is smaller than over liquid water. In this way ice crystals grow by condensation while drops tend to evaporate. Thus, if human activity emits ice nuclei to the atmosphere the precipitation distribution can be modified. Results of measurements show that in the vicinity of steel works and aluminum foundries the concentration of ice nuclei active at a temperature of — 20 °C is unusually high. It is believed that this is caused by the presence of some metal oxides in the air (Pruppacher, 1973). More recent studies on ice nuclei also showed that lead compounds (e.g. Pbl 2) in exhaust gases of vehicles also have ice nucleating ability. It is believed, however, that anthropogenic ice nuclei cannot play an important role, except in local scale processes (see Pruppacher, 1973). 

From a knowledge of the solubility rules (see Section 4.2) and the solubility products listed in Table 16.2, we can predict whether a precipitate will form when we mix two solutions or add a soluble compound to a solution. This ability often has practical value. In industrial and laboratory preparations, we can adjust the concentrations of ions until the ion product exceeds K p in order to obtain a given compound (in the form of a precipitate). The ability to predict precipitation reactions is also useful in medicine. For example, kidney stones, which can be extremely painful, consist largely of calcium oxalate, CaC204 (K p = 2.3 X 10 ). The normal physiological concentration of calcium ions in blood plasma is about 5 mM (1 mM = 1 X 10 M). Oxalate ions ( 204 ), derived from oxalic acid present in many vegetables such as rhubarb and spinach, react with the calcium ions to form insoluble calcium oxalate, which can gradually build up in the kidneys. Proper adjustment of a patient s diet can help to reduce precipitate formation. Example 16.10 illustrates the steps involved in precipitation reactions. 

Mates of Precipitate Formation and Particle Growth The rate at which a precipitate can be produced in a filterable form varies widely and depends upon the solution environment. In the case of the oxalates of calcium and magnesium for instance, both compounds have fairly low solubility products (2.3 x I0 mol dm for calcium oxalate and... 

Finally, the preparation method has a pronounced influence on the obtained products. In fact, the preparation of mixed oxides by traditional techniques (such as the pH controlled co-precipitation) does not result in single phases but several multi-component phases with various atomic ratios are obtained. In the system under investigation it seems to be impossible to obtain a contemporary precipitation of two components, like hydroxides or non soluble salts, instead non uniform precipitates are always obtained [11]. The thermal transformation of these precipitates gives compounds with a variable atomic ratio as a function of their local concentration in the precipitate. On the contrary, the sol-gel method can get to the formation of a truly homogeneous gel (atomic interdispersion), that is the precursor of a very well interdispersed final material. In all cases the calculated metal amounts and a good metal interdispersion have been verified by SEM-EDS microanalyses. 

Before we begin a discussion of nucleation dturing a precipitation, we need to explain some of the intricacies of precipitation. We first start with two solutions, one containing the cation of interest and the other the anion. Both involve soluble substances like nitrates or chlorides for the cations and acids or sodium compounds (or the like) for the anions. When the two solutions are combined, a precipitate will form if its aqueous solubility, as defined by its solubility product, is less than either of the cation and/or anion solubilities. What this means is that if we use two soluble solutions and combine them, a precipitate will form if it is insoluble in the aqueous solution. There are many examples of precipitate formation. We need to define the effect of exactly how the precipitation should be carried out in terms of phosphor preparation. 

Harmful to temperature-sensitive compounds and microorganisms Higher likelihood of precipitate formation... 

The rate is determined by the formation of the intermediate. Nickel is the most effective catalyst followed by cobalt and then copper. Iridium is also a catalyst, but manganese and iron are not. Dissolved metals have the greatest effect, followed by precipitated metal compounds and metal particles. The effect of particles increases with increasing surface area. 

Describe the equilibrium of a slightly soluble ionic compound in water, and explain the meaning of understand how a common ion and pH affect solubility and how to predict precipitate formation from the values of... 

If the attractive strength of the water molecules is not sufficient to break the ionic bonds, then the compound does not dissolve. While most ionic compounds dissolve in water, a number of them do not. Precipitation formation in a chemical reaction is related to these concepts. If, after mixing two separate solutions together, there are two kinds of ions present that form a stronger ionic bond than the strength of the solvation bonds to water molecules, the ionic bonds will form, and an undissolved compound (or precipitate) will result. 

Oxidation first produces soluble oxygenated compounds of molecular weights between 500 and 3000 that increase the viscosity of oil then they polymerize, precipitate, and form deposits. Oxidation also causes formation of low molecular weight organic acids which are very corrosive to metals. 

Prolonged oxidation of any phosphorus compound, followed by standing in water, converts it to phosphate(V). This can then be detected by the formation of a yellow precipitate when heated with... 

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