Turbid solutions, determination

A brown, deliquescent salt, yielding a turbid solution with water, due to the almost invariable presence of some basic salt. Regarding the quantitative determination, see the note under Palladium. 

If the flasks containing turbid solutions, after endpoint determination, were allowed to stand for 20 to 30 min, they would slowly clarify and could then be titrated with more CEES. It is... 

Obviously colorimetric determinations of pH in colored or turbid solutions are not very reliable. The color of the indicator should never be the same as the color of the liquid. For example, one should employ phenolsulfonephthalein for yellow solutions, and not p-nitrophenol. 

When the concentration of sulphate in the solution is sufficiently low, the barium sulphate formed after the addition of barium chloride does not coagulate to form a precipitate, but remains as a fine suspension producing a turbidity. The determination of small quantities of sulphate (or any other sulphur compound after oxidation to S04 ) is based either on comparison of the turbidity with a set of standards or on its photoelectric estimation [26-28]. This turbidimetric method for determining sulphate is simple and fast, but of rather low precision and sensitivity. 

The ketones, as a general class, were expected to solubilize the SMA copolymers. However, acetone, formed a turbid solution which contained a significant quantity of insoluble polymer as a precipitate in the case of the SMA ester. To determine whether the turbidity was the result of concentration, the samples were heated to 55°C which did not result in a uniform polymer/solvent system as seen in the case of benzyl alcohol. Therefore, it was concluded that the ketones reported in Table III exhibited a visibly hostile Interacton although the precipitate observed may have been unreacted maleic anhydride or styrene-maleic acid copolymer. 

An important application of derivative spectroscopy lies in the determination of analytes in turbid media. Turbid solutions usually present a continuous increase of the absorbance towards shorter wavelengths and, as a consequence, do not produce any sudden spectral change either in the first or in the second derivative spectrum. Phenol determination in wastewater was one of the first practical applications of the derivative spectroscopy in turbid media [19], Another study, more recent, deals with the evaluation of the second-derivative determination of nitrate and total nitrogen [20],... 

Use of potentiometry for pH titration allows analyses to be carried out in colored or turbid solutions. Also, it solves the problem of selecting the correct indicator for a particular acid-base titration. The endpoint can be determined more accurately by using a first or second differential curve as described earlier. It also permits pH titrations in nonaqueous solvents for the determination of organic acids and bases as described subsequently. In addition, it can be readily automated for unattended operation. 

Heptane miseibility in laequer solvents is determined by mixing equal amounts of the speeimen (laequer) and heptane. If a elear solution results after mixing, it indieates good miseibility. If a turbid solution results, either the heptane is immiseible with the tested speeimen or water is present in either component. 

Determine which are definite solvents (clear solutions) and non-solvents for the polymer at a given % weight concentration (say, 10-15%w) and note down examples of borderline solvent (turbid solutions). Very often this gives a clue to the area where solvency can be expected on a solubility map (Figure 2.10). Pairs of solvents and diluents are then selected which make cross-sections through this area. Approximately lOg of solution are weighed out accurately and titrated to a permanent turbidity with a diluent (or mixture of diluents). 

Turbid solutions always end up giving higher absorbance than what is determined by the color. 

The polymer solution of interest is then placed in the cell, and the scattering intensity i determined at 90°. The turbidity of the solution is determined through equation (A3.1.2).The turbidity is determined for several concentrations and extrapolated to zero concentration. For this simple experiment. 

Determination of the Neutralization Point by Conductivity.—Measurements of the electrical conductance can also be employed in order to determine the point of neutralization of an acid by an alkali, or vice vers and the method is of especial importance when dealing with coloured or turbid solutions, in which the change of colour of an indicator would be more or less masked. 

For ethyl alcohol, two volumes of dicycZohexyl are mixed with one volume of the alcohol, a thermometer is introduced, and the mixture heated until it becomes clear. The solution is then slowly cooled, with constant stirring, and the temperature is determined at which the opalescent solution suddenly becomes turbid so that the immersed portion of the mercury thread of the thermometer is no longer clearly visible. This is the C.S.T. The water content may then be evaluated by reference to the following table. 

Quantitative Analysis of All llithium Initiator Solutions. Solutions of alkyUithium compounds frequentiy show turbidity associated with the formation of lithium alkoxides by oxidation reactions or lithium hydroxide by reaction with moisture. Although these species contribute to the total basicity of the solution as determined by simple acid titration, they do not react with allyhc and henzylic chlorides or ethylene dibromide rapidly in ether solvents. This difference is the basis for the double titration method of determining the amount of active carbon-bound lithium reagent in a given sample (55,56). Thus the amount of carbon-bound lithium is calculated from the difference between the total amount of base determined by acid titration and the amount of base remaining after the solution reacts with either benzyl chloride, allyl chloride, or ethylene dibromide. 

Sodium thiosulfate is determined by titration with standard iodine solution (37). Sulfate and sulfite are determined together by comparison of the turbidity produced when barium chloride is added after the iodine oxidation with the turbidity produced by a known quantity of sulfate iu the same volume of solution. The absence of sulfide is iadicated when the addition of alkaline lead acetate produces no color within one minute. 

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