Sodium hydroxide dissolving in water

Benzenedisulfonic acid [831-59-4] (disodium salt), produced by the neutralization of the disulfonic acid with sodium sulfite [7757-83-7] is used in the manufacture of resorcinol [108-46-3] (1,3-benzenediol) (2), a chemical component found in mbber products and wood adhesives (72). The disodium salt is fused with sodium hydroxide, dissolved in water, and acidified to produce resorcinol, which is isolated via extraction (73). 

To the chlorobenzene solution is then added sodium hydroxide dissolved in water and the chlorobenzene is removed by a steam distillation. After all of the chlorobenzene is removed, the precipitate which forms during the distillation is removed by filtration and discarded. The solution is cooled and acidified with hydrochloric acid, precipitating a tan solid. This is removed by filtration and washed acid-free. It Is then treated with sodium bicarbonate solution to remove any acid present and is then washed with water to remove all traces of bicarbonate. After drying approximately a 75% yield of mexenone is obtained. 

WEB Consider the process by which sodium hydroxide dissolves in water ... 

Substances typical of acids and bases are, respectively, HCl and NaOH. Hydrogen chloride dissolves in water with practically complete dissociation into hydrated protons and hydrated chloride ions. Sodium hydroxide dissolves in water to give a solution containing hydrated sodium ions and hydrated hydroxide ions. Table 3.6 gives values of the mean ionic activity coefficients, y , at different concentrations and indicates the pH values and those expected if the activity coefficients are assumed to be unity. 

Sodium hydroxide dissolves in water to give OH (aq) ions, the strongest base which can exist in an aqueous system. Chloric(VII) acid (perchloric acid) dissociates practically completely in dilute solution to give H30+(aq) ions, which represent the strongest acid which can exist in an aqueous system. The amphoteric behaviour of aluminium is noticed in a series of hydrated salts containing the Al3 + ion and in compounds such as NaA102, which contains the aluminate(III) ion, AIO2-. 

As we have shown, when both hydrochloric acid and sodium hydroxide dissolve in water the ions separate completely. We may therefore write ... 

Solution 1 34.64 g of CuSOi SHjO dissolved in water and diluted to 500 mL. Solution II 173 g of sodium potassium tartrate (Rochelle salt) and 65 g of sodium hydroxide dissolved in water and diluted to 500 mL. 

Solutions of sodium hydroxide are made by adding the solid compound to water, and never water to the solid. The reason is that large amounts of heat are generated when sodium hydroxide dissolves in water. That heat is absorbed by water, but would not be... 

The flask pictured on the left in Figure 19-7 shows the reaction before adding a phase-transfer catalyst. Water forms the upper layer, and chloroform forms the lower layer. Sodium hydroxide dissolves in water but not in chloroform, so it is entirely in the water layer. Cyclohexene dissolves in chloroform but not in water, so it is entirely in the chloroform layer. Very little reaction occurs under these conditions, even when using a high-speed stirrer. 

A base is a substance that produces hydroxide ion and/or accepts H+. Many bases consist of metal ions and hydroxide ions. For example, solid sodium hydroxide dissolves in water to yield a solution containing OH ions ... 

The thymol can be separated by dissolving the product obtained by the sodium hydroxide fusion in water, acidulating with dilute sulphuric acid, and then steam distilling or it may be extracted with a suitable solvent or in any other appropriate manner. 

Dithioglycerol is prepared in the following manner 1,537 parts of sodium monosulfide nonahydrate and 411 parts of powdered sulfur are dissolved with stirring in 1,345 parts of water. Magnesium hydroxide is precipitated in the stirred sodium trisulfide solution by adding successively 97 parts of sodium hydroxide dissolved in 180 parts of water and then slowly 246 parts of magnesium chloride hexahydrate dissolved in 180 parts of water. The... 

A solution of 50 grams of N-(a-methylhomoveratryl)-3-methoxy-4-ethoxyphenylacetamide, prepared as set out above, in 200 cc of benzene, is treated with 8 cc of phosphorus oxychloride. The mixture is refluxed for about 3 hours, cooled and then is shaken with a solution composed of 15 grams of sodium hydroxide dissolved in 60 cc of water. The aqueous layer is removed, and the benzene solution is washed with water. The washed benzene solution is dried over anhydrous magnesium sulfate, filtered and evaporated to dryness. The low-melting solid residue is 6,7-dimethoxy-3-methyl-1-(3 -methoxy-4 -ethoxybenzyl)-dihydroisoquinoline base. 

FIGURE 14.17 A diaphragm cell tor the electrolytic production of sodium hydroxide from brine (aqueous sodium chloride solution), represented by the blue color. The diaphragm (gold color) prevents the chlorine produced at the titanium anodes from mixing with the hydrogen and the sodium hydroxide formed at the steel cathodes. The liquid (cell liquor) is drawn off and the water is partly evaporated. The unconverted sodium chloride crystallizes, leaving the sodium hydroxide dissolved in the cell liquor. 

In a 500-ml., three-necked, round-bottomed flask fitted with a mechanical stirrer and a thermometer is placed 42 g. (1.05 mole) of sodium hydroxide dissolved in 168 ml. of water. The contents of the flask are cooled to —20° and stirred vigorously as 48 g. (0.30 mole) of pyridinium-1-sulfonate (Note 1), which has been previously chilled to — 20°, is added in one portion. The mixture is stirred for 20 minutes while the temperature is kept below —5° (Note 2). The cooling bath is removed, and the mixture is stirred and warmed gradually to 20° over 20 minutes. The temperature of the dark orange mixture is then raised to 55-60° and after 1 hour is lowered again to —5°. The brown crystals that separate are filtered by suction, pressed into a compact filter cake, and washed with three 100-ml. portions of acetone (Note 3). The yield of this crude product amounts to 46-52 g. after drying on filter paper overnight or at 50° (1 mm.) for 1 hour. (Note 4). 

Sodium hydroxide, 10% in water. Dissolve 10 g of NaOH in 100 mL of distilled water Lead acetate, 30% in water. Dissolve 30 g of acetate in 100 mL of distilled water Stannous chloride solution. Dissolve 40 g of reagent in 100 mL of concentrated hydrochloric acid... 

A student wants to determine the enthalpy change associated with dissolving solid sodium hydroxide, NaOH, in water. The student dissolves 1.96 g of NaOH in 100.0 mL of water in a coffee-cup calorimeter. The initial temperature of the water is 23.4°C. After the NaOH dissolves, the temperature of the water rises to 28.7 C. 

To a flask are added with stirring 6.8 gm (0.06 mole) of 2-mercaptoethylamine hydrochloride in 35 ml of 95 % ethanol, 2.5 gm (0.06 mole) of sodium hydroxide dissolved in 4 ml of water, and then 6.8 gm (0.05 mole) of phenyl isothiocyanate. The temperature rises to about 39°C and then slowly drops to room temperature. After 2 hr at room temperature the mixture is poured into 200 ml of ice water, the solid is filtered, washed with water, and dried to give 9.7 gm (91 %), m.p. 105°-114°C of crude l-(2-mercaptoethyl)-3-phenyl-2-thiourea. The product is recrystallized twice from ethanol to give crystals melting at 113°-116.5°C. 

The submitters observed the separation of a pasty solid at this stage and added four 10-ml. portions of water during the addition of- the thiol, then dissolved the entire solid with approximately 240 ml. of water. Sometimes, at this point, as much as 10% of the added thiol separated out as a floating oil. The presence of this thiol affects the course of the reaction to yield symmetrical disulfides.2 In this case the organic layer should be separated, then added dropwise to an equivalent amount of sodium hydroxide dissolved in a minimum amount of water, and mixed with the original thiolate solution. 

The amine hydrochloride solution is evaporated nearly to dryness on a steam bath (Note 13) and transferred with about 300 ml. of water to a 1-1. threc-necked flask equipped with a stirrer,3 separatory funnel, and condenser. The stirrer is started, and the acid solution is cooled to 0° by immersing the flask in an ice bath. The amines are liberated by adding slowly 100 g. of sodium hydroxide dissolved in 250 ml. of water. 

Sodium aesenite is prepared by dissolving 226 g. (1.14 moles) of powdered arsenious oxide, made into a paste with a little water, in a solution of 275 g. (6.88 moles) of sodium hydroxide dissolved in 600 cc. of water. This solution, diluted with 600 cc. of water, is poured into a 2-1. three-neck flask, provided with a reflux condenser and a mechanical stirrer, and 150 g. (1.22 moles) of freshly distilled nitrobenzene is added (Note 1). 

Alkali metal alkoxides and phenoxides may be obtained by reacting the metal hydroxide with either alcohol or phenol. With alcohols the generated water must be removed, typically as an azeotrope, as with sodium hydroxide dissolved in ethanol-benzene followed by reflux.69 With the more acidic phenols the phenoxides of Li, Na, K, Rb and Cs are more readily formed by simply heating MOH in absolute ethanol with phenol followed by recrystallization.70"72... 

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