Hydroxide dilute

Wet-Chemical Determinations. Both water-soluble and prepared insoluble samples must be treated to ensure that all the chromium is present as Cr(VI). For water-soluble Cr(III) compounds, the oxidation is easily accompHshed using dilute sodium hydroxide, dilute hydrogen peroxide, and heat. Any excess peroxide can be destroyed by adding a catalyst and boiling the alkaline solution for a short time (101). Appropriate ahquot portions of the samples are acidified and chromium is found by titration either using a standard ferrous solution or a standard thiosulfate solution after addition of potassium iodide to generate an iodine equivalent. The ferrous endpoint is found either potentiometricaHy or by visual indicators, such as ferroin, a complex of iron(II) and o-phenanthroline, and the thiosulfate endpoint is ascertained using starch as an indicator. 

When warmed with barium hydroxide, dilute alkalis or acids, hyoscin is hydrolysed, yielding tropic acid and a new base, CgHjsOjN, oscine o scopoline. Depending on the conditions of experiment, the tropic aci obtained may be either the pure Z-form or the partially racemised acid but the oscine obtained is invariably inactive. 

Phosphorous-based fire retardants carbonised the circuit boards surface, preventing fresh materialbecoming available for burning. Mineral fire retardants, such as aluminium hydroxide, dilute the flammable organic compounds in the bulk material, cool the material and release water on heating. 

The submitter has synthesized nine alkyl phenyl selenides in yields of 85-95% by treating alcohol solutions of the sodium salt (the selenophenol is dissolved in the calculated amount of 50% aqueous sodium hydroxide diluted with alcohol) with the appropriate alkyl halide or sulfate. 

Procedure Weigh accurately about 0.8 g of granulated zinc, dissolve by gentle warming in 12 ml of dilute hydrochloric acid and 5 drops of bromine water. Boil to remove excess bromine, cool and add sufficient DW to produce 200 ml in a volumetric flask. Pipette 20 ml of the resulting solution into a flask and neutralize carefully with 2 N sodium hydroxide. Dilute to about 150 ml with DW, add to it sufficient ammonia buffer (pH 10.0) to dissolve the precipitate and add a further 5 ml quantity in excess. Finally add 50 mg of Mordant Black II mixture and titrate with the disodium edetate solution until the solution turns green. Each 0.003269 g of granulated zinc is equivalent to 1 ml of 0.05 M disodium ethylenediaminetetracetate. 

Dissolve 42 g of sodium hydrogen carbonate in about 500 ml of Dl water. Adjust pH to 8.5 using sodium hydroxide. Dilute to 1 I with Dl water. 

Cognate preparation. m-Nitrobenzyl alcohol. Clamp a 500-ml three-necked flask, equipped with a mechanical stirrer, a thermometer and a burette, above the bench so that an ice bath can be placed beneath it. Place a solution of 15.1 g (0.1 mol) of m-nitrobenzaldehyde (Expt 6.19) in 100 ml of methanol in the flask and, while stirring, add a solution of sodium borohydride (1.4g, 0.037 mol NaBH4 in 2 ml of 2 m sodium hydroxide diluted with 18 ml of water) at the rate of 0.5 ml per minute, with occasional cooling to keep the reaction at 18-25 °C. When about three-quarters of the solution has been added, there is no further tendency for the temperature to rise, and the addition is stopped. Treat a small portion of the reaction mixture with dilute sulphuric acid hydrogen should be evolved. 

Cognate preparations. l,2 4,5-Di-0-cyclohexylidene-D-fructopyranose. Add 200 g (1.11 mol) of finely powdered dry D-fructose with vigorous stirring to 419 g (440 ml, 4.49 mol) of ice-cooled cyclohexanone containing 30 ml of concentrated sulphuric acid the reaction mixture becomes solid within 30 minutes. Leave the mixture overnight at room temperature, dissolve the product in 500 ml of chloroform and wash the solution with dilute aqueous sodium hydroxide, dilute hydrochloric acid and water and finally dry and evaporate. Solidify the residue by m.p. 145-156°C, Md° —133.5° (cl in CHC13). The yield is 142 g (37%). 

It is noticed that when Fe3+OOR is formed in aprotic diluters (under strongly basic conditions) at low temperature, degradation products are synthesized by reaction (7.4) [29], However, in hydroxide diluters oxidants dissociate heterolytically by reaction (7.3) [30, 31], which is proved by the formation of the following products epoxides from alkenes and alcohols from ROOH. 

Assay Transfer about 10 g of sample, previously dried in vacuum at 70° for 4 h and accurately weighed, into a 100-mL volumetric flask, dissolve in 50 mL of water, add 0.2 mL of 15.2 N ammonium hydroxide, dilute to volume with water, and mix. After 30 min, determine the angular rotation [see Optical (Specific) Rotation, Appendix IIB] in a 100- or 200-mm tube at 25° with the sodium D line. The observed rotation, in degrees (absolute value), multiplied by 1.124 (or 0.562 for the 200-mmtube), represents the weight, in grams, of Fructose in the sample taken. 

Place the mixture in the water bath at 20°, and allow it to cool for exactly 30 min, then add 20.0 mL of 0.5 N sodium hydroxide, dilute to volume with water, and mix. 

Magnesium Sulfate Solution Dissolve 1.0 g of magnesium sulfate (MgS04-7H20) in 700 mL of water. Adjust the pH to 7.5 to 8.0 as specified by the manufacturer, using 1 N sodium hydroxide, dilute to 1000 mL with water, and mix. 

Buffer Solution Dissolve 6.8 g of monobasic potassium phosphate and 1.8 g of sodium hydroxide in 950 mL of water in a 1000-mL volumetric flask, adjust to a pH of 7.5 0.2, using 0.2 A sodium hydroxide, dilute with water to volume, and mix. Store this solution in a refrigerator. 

N Ammonium Hydroxide. Dilute 135 ml of concentrated ammonium hydroxide (28% as NH3) to 1000ml in a volumetric flask. This solution is stored in a Pyrex or borosilicate glass bottle and should be used only as long as it remains free from sediment when mixed with the sample of dissolved lignin in the procedure used to test reagent purity (Note 1). 

Any dilute solution of sodium sulfate may be used. If several runs are to be made, the solution recovered from the filtration of the hydrocinnamic acid should be neutralized with sodium hydroxide, diluted if necessary, and used again. Traces of hydrocinnamic acid contained in this solution are thus saved, c. p. chemicals are not necessary. 

Quinalizarin (0-05 %, in NaOH). Dissolve 0-05 g quinalizarin in a mixture of 50 ml water and 5 ml 2m sodium hydroxide. Dilute the solution with water to 100 ml. 

In an experimental study of mixed iron-silica colloids we found the opposite phenomenon, stabilization of colloids of iron hydroxide by silica colloids, which is manifested very clearly in undialyzed iron hydroxide sols of average concentration with a ratio of Fe203 SiOj = 1 3. Colloidal iron in mixed solutions proved to be more resistant to the action of electrolytes than in isolated sols of iron hydroxide. Only colloidal silica shows any stabilizing effect on sols of iron hydroxide dilute solutions undersaturated with Si(OH)4 are not stabilizers. It is characteristic that colloidal silica is capable of stabilizing colloidal iron in the same pH ranges in which pure silica sols are stable in acid (pH < 4) and alkaline (pH > 8) environments. In slightly acid environments (pH = 5-6) iron-silica sols are unstable and decompose to form mixed sediments, which sometimes are not uniform due to different rates of coagulation and deposition. 

M Ammonium hydroxide diluted 1 50 in deionized water 100% Ethanol. 

To 2.0 mL of 5% silver nitrate solution, add 1.0 mL of 10% sodium hydroxide in a test tube. To the gray precipitate of silver oxide, AgjO, add 0.5 mL of a 2.8% ammonia solution (10 mL of concentrated ammonium hydroxide diluted to 100 mL). Stopper the tube and shake it. Repeat the process until almost all of the precipitate dissolves (3.0 mL of ammonia at most) then dilute the solution to 10 mL. Empty the test tubes of sodium hydroxide solution, rinse them, and add 1 mL of Tollen s reagent to each. Add one drop (no more) of the substance to be tested by allowing it to run down the inside of the inclined test tube. Set the tubes aside for a few minutes without agitating the contents. If no reaction occurs, warm the mixture briefly on a water bath. As a known aldehyde try one drop of a 0.1 M solution of glucose. A more typical aldehyde to test is benzaldehyde. 

Tiie preparation of the first type of compounds, the tin trialkyl bromides, has already been given under tyj >e RgSnR (p. 303). The chlorides are formed from the corresponding bromides by dissolving the latter in 5 parts of ether and shaking the solution with half its volume of 33 per cent, alkali. This produces the hydroxide, dilute hydrochloric acid giving the chloride. For list of compounds of type RgR SnX, see Table XV. of Appendix. 

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