Diluting solutions

Ammonium Hydroxide Solution, Dilute, i vol. of cone, ammonia d, o-88o) to 3 vols. of water. 

Sodium Hydroxide, 10% Aqueous, ioo g. NaOH dissolved in water, and the cold solution diluted to i litre. 

In practice, it is best to purify a quantity, say one Winchester quart bottle, of technical 0 720 ether to cover the requirements of a group of students. The Winchester quart of ether is divided into two approximately equal volumes, and each is shaken vigorously in a large separatory funnel with 10-20 ml. of the above ferrous solution diluted with 100 ml. of water. The latter is removed, the ether transferred to the Winchester bottle, and 150-200 g. of anhydrous calcium chloride is added. The mixture is allowed to stand for at least 24 hours with occasional shaking. Both the water and the alcohol present are thus largely removed. The ether is then filtered through a large fluted filter paper into another clean dry Winchester bottle (CAUTION all flames in the vicinity must be... 

Dissolve 20 g, (19 -6 ml.) of anihne in a mixture of 55 ml. of concentrated hydrochloric acid (1) and 55 ml. of water contained in a 350 ml, conical flask. Place a thermometer in the solution and immerse the flask in a bath of crushed ice (2) cool until the temperature of the stirred solution falls below 5°, Dissolve 16 g. of sodium nitrite in 75 ml. of water and chUl the solution by immersion in the ice bath add the sodium nitrite solution (3) in small volumes (2-3 ml. at a time) to the cold anihne hydrochloride solution, and keep the latter weh stirred with the thermometer. Heat is evolved by the reaction. The temperature should not be allowed to rise above 10° (add a few grams of ice to the reaction mixture if necessary) otherwise appreciable decomposition of the diazonium compound and of nitrous acid wih occur. Add the last 5 per cent, of the sodium nitrite solution more slowly (say, about 1 ml. at a time) and, after stirring for 3-4 minutes, test a drop of the solution diluted with 3-4 drops of water with potassium iodide - starch paper (4) if no immediate blue colour... 

Dissolve 46-5 g. (45-5 ml.) of aniUne in a mixture of 126 ml. of concentrated hydrochloric acid and 126 ml. of water contained in a 1-htre beaker. Cool to 0-5° in a bath of ice and salt, and add a solution of 36-5 g. of sodium nitrite in 75 ml. of water in small portions stir vigorously with a thermometer (1) and maintain the temperature below 10°, but preferably at about 5° by the addition of a httle crushed ice if necessary. The diazotisation is complete when a drop of the solution diluted with 3-4 drops of water gives an immediate blue colouration with potassium iodide - starch paper the test should be performed 3-4 minutes after the last addition of the nitrite solution. Prepare a solution of 76 g. of sodium fluoborate (2) in 150 ml. of water, cool, and add the chilled solution slowly to the diazonium salt solution the latter must be kept well stirred (1) and the temperature controlled so that it is below 10°. Allow to stand for 10 minutes with frequent stirring. Filter... 

Study of the solubility behaviour of the compound. A semi-quantitative study of the solubility of the substance in a hmited number of solvents (water, ether, dilute sodium hydroxide solution, dilute hydrochloric acid, sodium bicarbonate solution, concentrated sulphuric and phosphoric acid) will, if intelligently apphed, provide valuable information as to the presence or absence of certain classes of organic compounds. 

Benzenesulphonyl chloride test. Proceed as in the benzoyl chloride test, but use 15-20 ml. of 5 per cent, sodium hydroxide solution. Examine the product when the odour of the sulphonyl chloride has disappeared. (If no reaction has occurred, the substance is probably a tertiary amine.) If a precipitate appears in the alkaline solution, dilute with about 10 ml. of water and shake if the precipitate does not dissolve, a secondary amine is indicated. If the solution is clear, acidify it cautioiosly to Congo red with dilute hydrochloric acid a precipitate is indicative of a primary amine. 

Alkaline arsenite, O.IA As(lll) to As(V). Dissolve 4.9460 g of primary standard grade AsjOj in 40 mL of 30% NaOH solution. Dilute with 200 mL of water. Acidify the solution with 6N HCl to the acid color of methyl red indicator. Add to this solution 40 g of NaHC03 and dilute to 1 L. 

Monobasic aluminum acetate is dispensed as a 7% aqueous solution for the topical treatment of certain dermatological conditions, where a combination of detergent, antiseptic, astringent, and heat-dispersant effects are needed (12). The solution, diluted with 20—40 parts water, is appHed topically to the skin and mucous membranes as a wet dressing (13). Burrow s solution, prepared from aluminum subacetate solution by the addition of a specific amount of acetic acid, is also used as a topical wet dressing. Standards of purity and concentration have been estabHshed for both pharmaceutical aluminum acetate solutions (13). Each 100 mL of aluminum subacetate solution yields 2.30—2.60 g of aluminum oxide and 5.43—6.13 g of acetic acid upon hydrolysis. For the Burow s solution, each 100 mL yields 1.20—1.45 g of aluminum oxide and 4.25—5.12 g of acetic acid. Both solutions may be stabilized to hydrolysis by the addition of boric acid in amounts not to exceed 0.9% and 0.6% for the subacetate and Burow s solutions, respectively (13). 

For predicting liquid diffiisivities of binary nonpolar liquid systems at high solute dilution, Umesi " developed a method that only depends on the viscosity of the solvent (2) and the radius of gyration of the solvent (2) and the solute (1). The Technical Data Book— Petroleum Refining gives the method and values of the radii of gyration for common hydrocarbons. Errors average 16 percent but reach 30 percent at times. 

For predic ting diffiisivities in binary polar or associating liquid systems at liign solute dilution, the method of Wilke and Chang " defined in Eq. (2-156) can be utilized. The Tyn and Cains equation (2-152) can be used to determine the molar volume of the solute at the normal boihng point. Errors average 20 percent, with occasional errors of 35 percent. The method is not considered to be accurate above a solute concentration of 5 mole percent. 

The electrodes have a wide linear response range to CrP" and Ni " ions concentration. For this reason, they are adequate for the potentiometric determinations of copper and nickel ions in diluted solutions (dilutions may go down to 10 M) as well as in checking the industrial waters. 

Chemical reaction - formation of intermetollic compounds Diffusion in solid solutions (dilute ideal solutions between solute 300 to 5 X 1 O ... 

Spray solution Dilute the dipping solution with methanol in a ratio of 1 + 2. 

Commercial Sodium Acetylide A suspension (30 ml) of sodium acete-lide (20% in exylene) is centrifuged and the solid brown sodium acetylide is taken up in 25 ml of dimethyl sulfoxide. To this is added a solution of 5 g of 5a-hydroxy-6j5-methylandrostane-3-17,dione 3-ethylene ketal in 85 ml of dimethyl sulfoxide. After stirring at room temperature overnight, ice is added and the solution diluted to about 250 ml. The tan precipitate is collected, washed with water and dried yield 4.8 g mp 202-204°. Crystallization from ethyl acetate gives a product of mp 204-206°. 

When the solution is just cold the crystals, previously le-moved, are sown evenly over the bottom of the dish at distances of I—2 cms. apart and left for two days. The crystals will have now grown to a size which will enable the facets to be readily recognised. Each crystal is dried and carefully examined with a pocket lens in order to determine the position of the hemi-hedral facets, and placed in separate heaps. These facets lie to the right or left hand of the central prism face, as shown in Fig. 74. The crystals should be weighed, dissolved, and the solution diluted and examined in the polarimeter. The specific rotation may then be calculated. See Appe7idix., p. 264. 

A solution of 192 g 3-acetylamino-2,4,6-triiodophenol, sodium (0.35 mol) in 350 ml di-methylacetamide, was mixed with 107.5 g 3-(2-iodoethoxy)-2-ethylpropionic acid ethyl ester (0.35 mol) at 90°C with stirring over a period of about 20 to 30 minutes. Stirring was continued while the mixture was held at 95°C to 100°C for 16 hours. The solvent was then removed by distillation in a vacuum, and the residue was poured into 4,000 ml water. The solid precipitate formed was recovered and washed with water, dilute sodium carbonate solution, dilute sodium bisulfite solution, and again with much water. The ethyl ester was obtained in a yield of 220 g (90%). When recrystallized from 75% aqueous ethanol, it melted at 80°C to 86°C. 

A solution of 1.5 grams of 17a-ethynyl estradiol in 50 cc of absolute ethanol is added slowly to a mixture of 3 grams of cyclopentyl bromide and 2 grams of potassium carbonate. This mixture is heated to reflux and stirred for 3 hours, then filtered. Most of the alcohol is eliminated by distillation and the resulting solution diluted with water, and cooled in an ice-bath. The product which precipitates Is collected by filtration, washed and dried. After recrystallization from methanol the 3-cyclopentyl ether of 17a-ethynyl estradiol shows a melting point of 107° to 108°C. 

Analyses, (a) Original zinc-ion solution. Dilute 2.00 mL (pipette) to 100 mL in a graduated flask. Pipette 10.0 mL of the diluted solution into a 250 mL conical flask, add ca 90 mL of water, 2 mL of the buffer solution, and sufficient of the solochrome black indicator mixture to impart a pronounced red colour to the solution. Titrate with standard 0.01 M EDTA to a pure blue colour (see Section 10.59). 

Procedure B. The experimental details for the preparation of the initial solution are similar to those given under Procedure A. Titrate 25 or 50 mL of the cold solution with standard 0.1M hydrochloric acid and methyl orange, methyl orange-indigo carmine, or bromophenol blue as indicator. Titrate another 25 or 50 mL of the cold solution, diluted with an equal volume of water, slowly with the standard acid using phenolphthalein or, better, the thymol-blue cresol red mixed indicator in the latter case, the colour at the end point is rose. Calculate the result as described in the Discussion above. 

The EGTA solution may be standardised by titration of a standard (0.05M) calcium solution, prepared by dissolving 5.00 g calcium carbonate in dilute hydrochloric acid contained in a 1 L graduated flask, and then after neutralising with sodium hydroxide solution diluting to the mark with de-ionised water, use zincon indicator in the presence of Zn-EGTA solution (see below). 

Pipette 25.0 mL of the potassium ion solution (about 10 mg K + ) into a 50 mL graduated flask, add 0.5 mL 1M nitric acid and mix. Introduce 20.0 mL of the sodium tetraphenylborate solution, dilute to the mark, mix, then pour the mixture into a 150mL flask provided with a ground stopper. Shake the stoppered flask for 5 minutes on a mechanical shaker to coagulate the precipitate, then filter most of the solution through a dry Whatman No. 40 filter paper into a dry beaker. Transfer 25.0 mL of the filtrate into a 250 mL conical flask and add 75 mL of water, 1.0 mL of iron(III) nitrate solution, and 1.0 mL of sodium thiocyanate solution. Titrate with the mercury(II) nitrate solution as described above. 

Lead (ca 100mg in 25 mL solution). Add 10 mL of freshly prepared reagent solution, dilute to 50 mL and add 12.5 mL of concentrated ammonia solution. 

Note. Prepare the ammonium molybdate reagent as follows. Dissolve 125 g ammonium nitrate in 125 mL water in a flask and add 175 mL nitric acid, sp. gr. 1.42. Dissolve 12.5 g ammonium molybdate in 75 mL of water and add this slowly and with constant shaking to the nitrate solution. Dilute to 500 mL with water, heat the flask in a water bath at... 

Buffer solution, dilute. To one volume of concentrated buffer solution, add five volumes water and adjust the pH to 6.1 by adding acetic acid or sodium hydroxide solution. 

If necessary, dilute the sample to give an ammonia concentration of 1 mg L 1 and fill a 50 mL Nessler tube to the mark. Prepare a series of Nessler tubes containing the following volumes of standard ammonium chloride solution diluted to 50 mL 1.0,2.0,3.0,4.0,5.0, and 6.0 mL. The standards contain 0.01 mg NH3 for each mL of the standard solution. Add 1 mL of Nessler s reagent to each tube, allow to stand for 10 minutes, and compare the unknown with the standards in a Nessler stand (Section 17.4) or in a BDH Nesslerimeter. This will give an approximate figure which will enable another series of standards to be prepared and more accurate results to be obtained. 

Treat the colourless solution (ca 15mL), free from interfering substances and about 1M in sulphuric acid, with 1 mL of 30 per cent hypophosphorous acid solution and 1 mL of 10 per cent aqueous potassium iodide solution. Dilute to 25 mL and match the yellow colour produced against standards containing the same concentrations of sulphuric acid and hypophosphorous acid. Alternatively, measure the absorbance at or near 460 nm or with a blue filter. 

Dissolve a known weight (ca 0.5 g) of the steel by any suitable procedure. Treat the acidic sample solution (< 200 /jg Co), containing iron in the iron(II) state, with 10-15 mL of 40 per cent (w/v) sodium citrate solution, dilute to 50-75 mL and adjust the pH to 3-4 (indicator paper) with 2M hydrochloric acid or sodium hydroxide. Cool to room temperature, add 10 mL of 3 per cent (10-volume) hydrogen peroxide and, after 3 minutes, 2mL of the reagent solution. Allow to stand for at least 30 minutes at room temperature. Extract the solution in a separatory funnel by shaking vigorously for 1 minute with 25 mL of chloroform repeat the extraction twice with 10 mL portions of chloroform. Dilute the combined extracts to 50 mL with chloroform and transfer to a clean separatory funnel. Add 20 mL of 2M hydrochloric acid, shake for 1 minute, run the chloroform layer into another separatory funnel, and shake for 1 minute with 20 mL of 2M sodium hydroxide. Determine the absorbance of the clear chloroform phase in a 1 cm cell at 530 nm. 

The iron may also be reduced with hydroxylammonium chloride. Add 5 mL of the 10 per cent hydroxylammonium solution, adjust the pH of the slightly acid solution to 3-6 with sodium acetate, then add 4mL of the 1,10-phenanthroline solution, dilute to 50 mL, mix, and measure the absorbance after 5-10 minutes. 

Reagents. Standard lead solution. Dissolve 0.160 g of analytical grade lead nitrate in 1 L of distilled water 10.0 mL of this solution, diluted to 250 mL gives a working solution containing 4 pg of lead mL"1. 

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