Sodium hydroxide

“ During electrolysis, oxygen is evolved at the anode and escapes from the outer vessel, while the sodium deposited in globules on the cathode floats upwards into the iron cylinder, within which it accumulates, and from which it may be re- moved at intervals by means of a perforated iron ladle, the fused salt, but not the metal, being able to pass freely through the perforations. The sodium is then cast into moulds. Sodium hydroxide has certain advantages compared with chloride, although it is more costly ”

“ The sodium chloride has obviously been partially decomposed, by the water, into its base and its acid; the decomposition is favored by the high temperature and by the fact that the hydrogen chloride [p180] formed can pass through the steam cushion into the water, while the sodium hydroxide is left behind. ”

“ This reaction is vigorously exothermal, i.e. it is accompanied by the evolution of heat. If a sufficient quantity of water be taken the whole of the sodium hydroxide, NaHO, formed is dissolved, and about 42,500 units of heat are evolved per 23 grams of sodium taken. As 40 grams of sodium hydroxide are produced, and they in dissolving, judging from direct experiment, evolve about 10,000 calories; therefore, without an excess of water, and without the formation of a solution, the reaction would evolve about 32,500 calories. ”

“ N/NaOH equals 0.0510 anhydride.
(B) Pure Fused Sodium Acetate.—The purchased salt is again completely fused in a platinum, silica or nickel dish, avoiding charring, powdered quickly and kept in a stoppered bottle or desiccator. It is most important that the sodium acetate be anhydrous.
(C) A Solution of Caustic Soda for Neutralizing, of about N/1 Strength, Free from Carbonate.—This can be readily made by dissolving pure sodium hydroxide in its own weight of water (preferably water free from carbon dioxide) and allowing to settle until clear, or filtering through an asbestos or paper filter. ”

“ If the sodium sulfite solution contains an excess of alkali, a black tar tends to form when the solution is warmed, and very little phenylhydrazine is obtained. Great care must be taken in determining the end point in the neutralization of the sodium hydroxide by the sulfur dioxide.
If the sodium sulfite-diazonium salt mixture is acidified before warming or before becoming dark, the red color of the solution does not disappear on heating, and the precipitated phenylhydrazine hydrochloride obtained is colored red. ”

“ Nitric and hydrochloric acids give a still greater expansion than sulphuric acid, and potassium hydroxide than sodium hydroxide, whilst a solution of ammonia gives a contraction. The relation to water must be considered as the cause of these phenomena. When sodium hydroxide and sulphuric acid dissolve in water they develop heat and give a vigorous contraction ”

“ Chemically, calcium hydroxide is a moderately strong base, though not so strong as sodium hydroxide. Owing to its cheapness it is much used in the [Pg 304] industries whenever an alkali is desired. A number of its uses have already been mentioned. It is used in the preparation of ammonia, bleaching powder, and potassium hydroxide. It is also used to remove carbon dioxide and sulphur compounds from coal gas, to remove the hair from hides in the tanneries (this recalls the caustic or corrosive properties of sodium hydroxide) , and for making mortar. ”

“ Its specific gravity is 2·13; [30] it is easily soluble in water, with disengagement of a considerable quantity of heat. [31] A saturated solution at the ordinary temperature has a specific gravity of about 1·5, contains about 45 per cent. of sodium hydroxide, and boils at 130°; at 55° water dissolves an equal weight of it. [32] Caustic soda is not only soluble in [530] water but in alcohol, and even in ether. Dilute solutions of sodium hydroxide produce a soapy feeling on the skin because the active base of soap consists of caustic soda. [33] Strong solutions have a corroding action. ”

“ The sodium arsenite may be prepared from pure arsenious oxide, as described below, and is stable for considerable periods; but commercial oxide requires resublimation to remove arsenic sulphide, which may be present in small quantity. To prepare the solution, dissolve about 5 grams of the powdered oxide, accurately weighed, in 10 cc. of a concentrated sodium hydroxide solution, dilute the solution to 300 cc., and make it faintly acid with dilute hydrochloric acid. Add 30 grams of sodium bicarbonate dissolved in a little water, and dilute the solution to exactly 1000 cc. in a measuring flask. ”

“ A solution once thoroughly mixed remains uniform.]
[Note 2: Commercial sodium hydroxide is usually impure and always contains more or less carbonate; an allowance is therefore made for this impurity by placing the weight taken at 23 grams per liter. If the hydroxide is known to be pure, a lesser amount (say 21 grams) will suffice.]
COMPARISON OF ACID AND ALKALI SOLUTIONS PROCEDURE.—Rinse a previously calibrated burette three times with the hydrochloric acid solution, using 10 cc. ”

“ It is only slightly soluble in water, alcohol, chloroform, liquid petrolatum and vegetable oils. Alkalies and strong acids decompose it. It is stable at temperatures below 120 C.
When about 1 gm. of the salt is boiled with 10 c.c. of sodium hydroxide test solution, the liquid filtered, and the filtrate acidulated with sulphuric acid, the white curdy precipitate produced, when washed and dried, melts at 90 to 95 C. (tri­brom­phenol) . The contents of the filter dissolve completely in dilute hydrochloric acid (insoluble inert material) . ”

“ A sample of sodium carbonate containing sodium hydroxide weighs 1.179 grams. It is titrated with 0.30 N hydrochloric acid, using phenolphthalein in cold solution as an indicator and becomes colorless after the addition of 48.16 cc. Methyl orange is added and 24.08 cc. are needed for complete neutralization. What is the percentage of NaOH and Na_{2}CO_{3}? ”

“ On adding the alkaline hydroxide to the solution, this hydrate is supposed to lose water, yielding the syn-diazo hydroxide, which then gives rise to a certain amount of the sodium salt (A. Hantzsch, Ber., 1898, 31, p. 1612) ,
This assumption also shows the relationship of the diazonium hydroxides to other quaternary ammonium compounds, for most of the quaternary ammonium hydroxides (except such as have the nitrogen atom attached to four saturated hydrocarbon radicals) are unstable, and readily pass over into compounds in which the hydroxyl group is no longer attached to the amine nitrogen ”

“ Of sodium and potassium hydroxide, it may be said that they can be used with all indicators, and their solutions may be boiled, but they absorb carbon dioxide readily and attack the glass of bottles, thereby losing strength; sodium carbonate may be weighed directly if its purity is assured, but the presence of carbonic acid from the carbonate is a disadvantage with many indicators ”

“ Sodium hydroxide, 0.01 N. 9. Sodium sulfite, 1.13 M. Prepare fresh immediately before use. 10. Water, deionized, then distilled. 11. Hydrogen, prepurified. 12. Air, filtered. 13. Helium, purified. 14. ”

“ Among the metals of the alkalis, the most widely distributed in nature, after sodium, is potassium. Like sodium, it does not appear either in a free state or as oxide or hydroxide, but in the form of salts, which present much in common with the salts of sodium in the manner of their occurrence. The compounds of potassium and sodium in the earth's crust occur as mineral compounds of silica. With silica, SiO2, potassium oxide, like sodium oxide, forms saline mineral substances resembling glass. ”

“ If silver hydroxide have acid properties, the addition of an alkali must suppress the hydrogen-ion and the hydroxide will go into solution as an argentate, MeAgO. We find, however, that sodium or potassium hydroxide, which would form an argentate very much more readily than ammonium hydroxide, has no solvent action on silver hydroxide (exp.) ; on the contrary, quantitative experiments show that the alkali makes the hydroxide still less soluble than in pure water—as demanded by the solubility-product for the basic ionization. ”

“ A fragment thrown on the surface of water rapidly disengages hydrogen, which gas, however, does not inflame, as happens with potassium; but inflammation occurs if hot water be used, or if the metal be dropped on moist filter paper. Sodium also combines directly, sometimes very energetically, with most non-metallic elements. It also combines with dry ammonia at 300-400° to form sodamide, NaNH 2 , a white waxy mass when pure, which melts at 155°. Heated in a current of carbon dioxide sodamide yields caustic soda and cyanamide, and with nitrous oxide it gives sodium azoimide ”

“ Such distinctions between the elements, according to their power of giving one or several saline forms, is a radical property of no less importance than the basic or acid properties of their oxides. Sodium as a typical metal does not form any acid oxides, whilst chlorine, as a typical non-metal, does not form bases with oxygen. Therefore sodium as an element may be thus characterised: it forms one very stable salt-forming oxide, Na2O, having powerful basic properties, and its salts are of the general formula, NaX, therefore in its compounds it is, like hydrogen, a basic and univalent element. ”

“ Sodium is a soft silver-white metal, scarcely solid at common temperatures, fuses at 194° Fahr., and volatilises at a red heat; it oxidises very rapidly in the air; when placed on the surface of cold water, it decomposes that liquid with great violence, but generally without flame, in which it differs from potassium; on hot water it burns with a bright yellow flame—in both cases a solution of pure soda being formed. Sp. gr. ”

“ There is one substance which will produce that yellow light; it is a curious metal called sodium—a metal so soft that you can cut it with a knife, and so light that it will float on water; while, still more strange, it actually takes fire the moment it is dropped on the water. It is only in a chemical laboratory that you will be likely to meet with the actual metallic sodium, yet in other forms the substance is one of the most abundant in nature. Indeed, common salt is nothing but sodium closely united with a most poisonous gas, a few respirations of which would kill you. ”

“ If it be heated in oxygen gas in excess, it burns, and is converted into the peroxide of sodium, which, when mixed with combustible bodies, and exposed to the action of heat, deflagrates with violence, giving off its excess of oxygen, and becoming changed into soda, or protoxide of sodium.
Experiment 64. When sulphuret of sodium is mixed with chlorate of potassa, and struck with a hammer, a detonation will ensue; and when sodium is heated nearly to fusion, in contact with sulphuretted hydrogen gas, it will unite with the sulphur; flame will be produced, and hydrogen gas set at liberty. ”

“ When the charge in a cylinder is exhausted, a fresh one is introduced by removing the plug, taking out the residue, and inserting a new supply of the mixture made up in a canvas bag. The operation is therefore continuous, and the metal obtained is nearly pure, as sodium does not exhibit the same tendency as potassium to form compounds with carbonic oxide.
Potassium and sodium are extremely soft metals; they are lighter than water, upon which they float, at the same time rapidly decomposing that compound by displacing half the hydrogen, which is set on fire by the heat. ”

“ With oxygen it forms two oxides; with chlorine, a chloride (common salt) ; and—with bromine, iodine, fluorine, &c., bromide, iodide, fluoride, &c., all of which may be obtained by similar processes to the respective compounds of potassium, which, for the most part they resemble.
Uses. Until recently sodium has been regarded as a mere mechanical or philosophical curiosity; it has now, however, become of great practical importance, from being employed in the manufacture of the metals aluminium, magnesium, &c. ”

“ Every molecule of water has two atoms of hydrogen linked up with one of oxygen, but sodium does not like two atoms of hydrogen: it insists on having one only. Accordingly the oxygen atom from the water, together with one of the hydrogen atoms, join forces with the sodium atom into a molecule of a new substance, a most valuable substance in many manufactures, called Caustic Soda, while the odd atom of hydrogen, deprived of its partners, has nothing left to do but to cling for a while to the cathode and finally float up and away. ”

“ If sodium be thrown on to water, caustic soda is produced, a substance made up of hydrogen, oxygen, and the simple radicle sodium; by another reaction a substance can be obtained consisting of hydrogen, oxygen, and the compound radicle nitryl (NO2) . These two bodies have analogous formulæ, Na OH and (NO2) OH, they may both be regarded as derived from water, H HO, by the replacement of one half of the hydrogen by a radicle; in one case by Na, in the other by NO2. Again, the whole of the hydrogen in water may be replaced by sodium, with production of the compound sodium oxide, Na2O. ”

“ Sodium is the metallic base of soda. It is silver white with a high lustre; crystallizes in cubes; of the consistence of wax at ordinary temperatures, and completely liquid at 194°, and139 volatilizes at a bright red heat. It is very generally diffused throughout nature though apparently somewhat less abundantly than potassium in the solid crust of the globe.
Salt, the chloride of sodium, a natural compound of one atom of chloride and one of sodium. It occurs as a rock inter-stratified with marl, and sandstones, and gypsum, and as an element of salt springs, sea water, and salt water lakes. ”