Turbidity appearance

To 100 ml of an isopropanol solution containing 11.8 grams of hyoscyamine base were added drop by drop with stirring 10 ml of an isopropanol solution containing 11 grams of p-n-butoxybenzyl bromide. After a while, the reaction mixture had a turbid appearance followed by separation of white crystals. 

The filtrate should possess a yellow or orange colour, indicating the presence of excess of precipitant. If a turbidity appears, a portion should be heated if the turbidity disappears, it may be assumed to be due to excess of reagent crystallising out, and is harmless. Otherwise, more reagent should be added, and the solution filtered again. 

Turbidity of the sonicated (30 min), control and boiled samples were measured and given in Table 9.19. As could be seen, the turbidity increased gradually, as the volume of solution or of CH3COONa increased in all solutions (control, sonicated and boiled). When 20 ml of Al3+ was sonicated for 30 min with 5 ml of CH3COONa, turbidity did not appear, but when a solution containing, 10 ml of Al3+ and 2.5 ml of CH3COONa was sonicated for the same duration, the turbidity appeared, indicating the role of ultrasonic power which decreased to about half as the volume of the solution increased. 

Benzenesulphonamide.—Finely powdered ammonium carbonate (10 g.) and benzenesulphonyl chloride (about 1 c.c.) are ground in a porcelain basin which is then warmed over a small flame until the odour of the sulphochloride has disappeared the mixture is well stirred meanwhile. After cooling, water is added and the product is collected at the pump, washed several times with water, and then crystallised from alcohol by adding hot water until a turbidity appears. Melting point 156°. 

Experiment. E. Fischer s Indole Synthesis.—Mix 2 g. of phenylhydrazine with 2 c.c. of acetone in a test tube. Water is eliminated and a turbidity appears. Suspend the tube in the boiling water bath for forty-five minutes, then add 6 g. of dry zinc chloride and heat the mixture for a few minutes with stirring in an oil bath at 180°. Now wash the dark-coloured melt into a small round-bottomed flask with four volumes of dilute hydrochloric acid and separate the resultant a-methylindole by distillation with steam. The substance collects as an oil which soon solidifies. After drying crystallise it from a little petrol ether. Melting point 59°. 

Measure the volumes of the solutions as accurately as possible and pour them together in pairs. Use a stop watch or a metronome to note the time interval after which turbidity appears. What is the turbidity of the solution caused by Write the equations of the reactions. Enter the results in your laboratory notebook using Form 7. 

Pour 10 ml of a 2.5% sulphuric acid solution into each of three dry beakers, and 10 ml of a 5% sodium thiosulphate solution into each of three other beakers. Measure the volumes as accurately as possible, using small measuring cylinders or burettes. Run the first experiment at room temperature. Rapidly pour the sulphuric acid solution into the sodium thiosulphate one. Record the time of pouring the solutions together with the aid of a stop watch or a metronome. Consider the instant when a[hardly noticeable turbidity appears at the end of the reaction. 

Quantitative Determination.— Dissolve. 1 gm. of pnlits.sinin cyanide in water and dilute to IOO cc. Dilute 10 ee, of this solution with 90 cc. of water, add a grannie of sodium chloride, and titrate with dcciriormal silver nitrate solid inn until a permanent, whitish turbidity appears. 

Ignite the sample by switching the current on in tbe same manner as when detg the heat of combustion. After cooling the bomb, wipe it off and roll on a flat surface for 5mins to insure that all C02 is absorbed by KOH. Open the release valve slightly and allow some of the gas to bubble thru a Ba hydroxide so In. If no turbidity appears,it means that all C02 in the bomb has... 

Sodium (2-3 gms.) is dissolved in alcohol (30 gms.), and to the cold solution is added malonic ethyl ester (16 gms.). To the clear mixture, ether is added till a turbidity appears, and then iodine (12-7 gms.),... 

Thirteen milliliters (0.127 mole) of 2,4-pentanedione is added dropwise to a slurry of 9.00 g. (0.0386 mole) of anhydrous zirconium(IV) chloride in 100 ml. of refluxing benzene. After a 4-hour reaction time, the condenser is removed to allow about half of the solvent to boil away, and then hot hexane is added to the clear, pale yellow solution until turbidity appears. The nitrogen flow is maintained throughout the entire operation. The flask is then stoppered and cooled in an ice bath. The yield of colorless, prismatic crystals is 15.6 g. (95%). The product is recrystallized twice from benzene-hexane as described in Sec. A, washed with two 50-ml. portions of hexane, and finally dried in vacuo at 80°C. for half an hour. (The checkers obtained about 7 g. of purified product.) Anal. Calcd. for Zr(C H702)sCl C, 42.49 H, 4.99 Cl, 8.36 Zr, 21.51. Found C, 42.26 H, 5.00 Cl, 8.36 Zr, 21.82. 

Laboratory Record. The working directions, in the section entitled procedure, are to be kept at hand while carrying out the manipulations. These directions do not need to be copied in the laboratory note book but it is essential, nevertheless, to keep a laboratory record in which are entered all important observations and data, such, for example, as appearance of solutions (color, turbidity) appearance of precipitates or crystals (color, size of grains, crystalline form) results of all weighings or measurements number of recrystallizations results of test for purity of materials and products, etc. 

A number of features of these data merit attention. First, the rise in turbidity is rather abrupt, taking place within ca. 0.3 pH units. Thus, there appears to be a well-defined critical pH below which no association is observed. Turbidity values in the range 100-%T<30 are stable for at least several hours and curves such as those in Figure 1 are readily reversible, both observations suggestive of an equilibrium system. Turbidity appears to result from coacervation centrifugation at... 

The titration of protein with polymer, shown in Figure 6, exhibits very different features than the titration curve of Figure 5. Turbidity appears at once and, initially, exhibits a linear dependence on PDMDAAC concentration. The rate of turbidity development subsequently increases about four-fold, and then diminishes slightly. We may speculate that, in the presence of excess protein, all polyions... 

While the distillation is continuing, two or three crystals of barium chloride are added to the distillate in the first Erlenmeyer flask. This distillate is then boiled gently for several seconds to remove carbon dioxide as well as to ascertain if any turbidity appears (Note 6). If the distillate remains clear, it is titrated with standard 0.01 N sodium hydroxide solution after addition of four to five drops of the phenolphthalein solution (Note 7). All further distillates are treated as described above. If less than 4ml of the standard alkali solution are required for the titration of the first distillate, the next 10ml of distillate is similarly titrated. If the acetic acid in the initial distillate consumes more than 4ml of standard alkali then three additional 5-ml distillates are collected and individually titrated as described above. When the indicator changes color upon the addition of the first drop of the alkaline solution, the analysis is complete. 

Place a drop of the neutral or acetic acid test solution on a black spot plate, and add a drop of 01m silver nitrate solution and a small amount of finely powdered sodium hexanitritocobaltate(III). A yellow precipitate or turbidity appears. 

In a water-CCl4 two-phase system under sonication, turbidity appeared through both emulsification and CI2 formation. 

Figure 22. Time required for turbidity appearance in a sunflower oil stored at 0°C as a function of the wax content [based on (58, 59)].

Consequently, other factors than the wax content influence the time required for the appearance of turbidity. Figure 22 shows the time required for turbidity appearance in sunflower oil stored at 0°C as a function of the wax content. All oils passed the cold test, i.e., remained clear after 5.5 hours at 0°C, except the sample containing 80 ppm of wax (58, 59). Turbidity develops in an oil containing 6 ppm of wax after 10 days, that is, a longer time period than that considered by the cold test. 

The phenomenon of turbidity appearance in sunflower oil is complex. The time necessary for mrbidity appearance for a given wax content depends on the tempering temperature. Both the time necessary for the appearance of mrbidity at temperatures above 0°C and the minimum concentration causing turbidity may be expected to increase with temperature. However, the wax crystallization rate is reported to be the highest at 13°C, i.e., the time necessary for the appearance of visible mrbidity in an oil is the shortest at this temperamre (58, 59). In view of the above difficulties,... 

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