Precipitation indicator

Fig. 25.3. Mineralogical consequences of mixing Fountain brine into the Lyons formation. Vertical axis shows changes in mineral volume, expressed per kg of Lyons groundwater positive changes indicate precipitation and negative, dissolution.

Fast solution reactions between analyte and a reagent titration to stoichiometric point by volumetric or coulometric methods end-point detection by visual indicators, precipitation indicators or electrochemical means. 

The simulations indicate precipitation of the carbonate minerals calcite (CaC03), dolomite... 

Figure 2. Transverse section of sample from inside neck of the Anahita Rhyton (CM A 62-294). Structure illustrates darker etching grains (muddy), indicating precipitation of copper-rich phase (X55).

Give balanced ionic equations for the following reactions in aqueous solution. If a reaction does not occur, write NR. Indicate precipitates by J. and gases by f. 

Fig. 22 Static light scattering close to the precipitation threshold. Measurements are performed at constant [Ca2+] by decreasing [NaPA] (route 1). The inert salt level is 0.1 M NaCl. Squared mean square radius of gyration is plotted vs. [NaPA], The symbols denote four different Ca2+ concentrations 3.25 mM ( ) 3.5 mM ( ) 3.75 mM (A) 4.0 mM ( ). Vertical lines indicate precipitation limits which appear as open circles in Fig. 23...

For those cases where a reaction occurred, write a complete and balanced equation. Indicate precipitates, gases, and color changes. Table 8.2 lists some insoluble salts. For those cases where no reaction took place, write No Reaction. ... 

Precipitated particles lead to an increase in UV absorbance due to light scattering. Lipinsky used a diode array UV (Hewlett Packard HP8452) at 600-820 nm for their experiment. UV absorbance (y-axis) vs. p,L DMSO plots (x-axis) is used to detect the precipitation point. A strong increase in the slope of the curve indicates precipitation. Precipitation defines the maximum solubility level in this experiment. The method allows a classification between poor, moderate and good... 

Samples were collected biweekly from May 1996 to May 1997. Hydrologic water volumes are averages from 1991 to 1994 and indicate precipitation inputs and water evapotranspired between 300 and 750 cm. 

A phthalocyanine core was functionalized with four, eight, and 16 ferrocenyl units (compounds 49-51) [67]. Cyclic voltammetry experiments in DMF or CH2CI2 showed the presence of many quasi-reversible waves. All the ferrocenyl units behave independently, giving rise in all three compounds to a single oxidation wave, which is accompanied by one or two oxidation and by two or three reduction processes due to the phthalocyanine rt-system. For 51, the presence of a stripping peak indicates precipitation of the oxidized product in CH2CI2, as often observed in ferrocene-functionalized dendrimers (see Section 9.4.1). 

Both the previous approaches apply to discontinuous GAS process (in which the pressure progressively increases) and indicate precipitation process pressures between 50 and 70 bar, i.e., under subcritical conditions (even when the critical pressure of pure CO2 is considered), whereas the experimental evidences for semi-con-tinuous SAS (steady-state pressure) indicate larger pressure values for the precipitation of micro- and nano-particles."... 

The 6 0 values of precompactional calcite cements (-10.2%o to -4.8%o) (Table 1) indicate precipitation at temperatures of 10-30°C, from meteoric pore waters with 6 0 of -5%o (Fig. 19). The range obtained may reflect either true changes in mean annual air temperature or variations in 6 0 of pore waters due to fluctuations in dry and wet periods (see Cerling, 1984). Heavy rainfall, for examplfe, may have lower S 0 values than mean annual rainfall (Vogel Van Urk, 1975). 

At the peak removal of calcium, the effluent is supersaturated with gypsum, which will precipitate after removal from the bed. The dashed line in Figure 7 shows the calcium level reached after standing for one week. Undisturbed samples became opalescent, indicating precipitation, about an hour after sampling. In spite of the gypsum supersaturation, no trouble was ever experienced with precipitation in the bed, in the porous carbon bed support, or in the effluent piping from the pilot plant. 

Study of the morphological features of EEC indicate precipitation in the course of the epoxy resin cm"e of particles of the discrete phase of the rubber, the dispersion of which in the epoxy polymer matrix has a considerable effect on the mechanical properties of the latter. If the rubber particles are large enough, they can be detected by optical microscopy, but the most important results are obtained by electron microscopy. 

Often, the desired solubility characteristics for a particular compound are not found in a single solvent. In these cases, a mixed solvent may be used. You simply select a first solvent in which the solute is soluble and a second solvent, miscible with the first, in which the solute is relatively insoluble. The compound is dissolved in a minimum amount of the boiling solvent in which it is soluble. Following this, the second hot solvent is added to the boiling mixture, dropwise, until the mixture barely becomes cloudy. The cloudiness indicates precipitation. At this point, more of the first solvent should be added. Just enough is added to clear the cloudy mixture. At that point, the solution is saturated, and as it cools, crystals should separate. Common solvent mixtures are listed in Table 11.3. 

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