Nitric acid nascent

Reaction CXVI. Action of Nascent Nitric Acid on Aromatic Compounds in presence of Concentrated Sulphuric Acid.—This reaction gives nitro compounds which, in many cases, are only obtained with difficulty by the action of mixed acid. Sodium or potassium nitrate is usually added to the solution of the compound in cone, sulphuric acid. It is usually necessary to keep the temperature below ordinary room temperature. 

Zinc is a much more powerful reducing agent than copper furthermore, zinc displaces from an acid, hydrogen, which, at the moment of its displacement, is in the atomic or nascent condition, and especially active. Under these conditions the nitrogen is reduced to its lowest valence, which is shown in ammonia. The ammonia does not escape from the solution because it combines with the excess of nitric acid. 

Hydroxyl Amine.—The first compound is an ammonia derivative, and is known as hydroxyl amine. When nitric acid is reduced by nascent hydrogen a compound is obtained, the composition of which is NH3O and which proves to be a hydroxyl substitution product of ammonia, NH2—OH or hydroxyl amine. It may be looked upon as ammonia in which one hydrogen has been oxidized to hydroxyl. It thus stands between nitric acid and ammonia which are reciprocal oxidation and reduction products. 

In the paraffin series this reaction and the products formed are not of especial importance but we shall find that in the benzene or carbo-cyclic series the nitro compounds are easily formed directly from the hydrocarbons by action of nitric acid and they are very important compounds. When nitro methane is reduced by nascent hydrogen the nitro groupj (—NO2), the nitric acid residue, is reduced to the ammonia residuej (—NH2). The result is an alkyl amine. 

Oxidizing agents decompose HCl with liberation of Cl. A mixture of hydrochloric and nitric acids in the proportion of three molecules of the former to one of the latter, is the aoidum nitro-hydrochloricum U. S. Br. or aqua regia. The latter name alludes to its power of dissolving gold, by combination of the nascent Cl, which it liberates, with that metal, to form the soluble auric chlorid. 

Chemical.—Heated in air it is converted into the trioxid and ignites somewhat below a red heat. In O it bums with a brilliant, bluish-white light. In dry air it is not altered, but in the presence of moisture its surface becomes tarnished by oxidation. In HjO it is slowly oxidized, a portion of the oxid dissolving in the water. It combines readily with Cl. Br, I, and S, and with most of the metals. With H it only combines when that element is in the nascent state. Warm, concentrated HjSO, is decomposed by As, with formation of SO , AsjOs, and HjO. Nitric acid is readily decomposed, gi-t-ing up its O to the formation of arsenic acid. With hot HCl, arsenic trichlorid is formed. When fused with potassium hydroxid, arsenic is oxidized, H is given oflf, and a mixture of potassium arsenite and arsenid remains, which by greater heat is converted into arsenic, which volatilizes, and potassium arsenate, which remains. 

Sulfonal — Diethylsulfondimethylmetliane — qh / vIo c h . —is obtained by the oxidation of ethyl-mercaptol, prepared as above described, by potassium permanganate. It crystallizes in thick, colorless prisms, dilBcultly soluble in cold water or alcohol, readily soluble in hot water or alcohol, and in ether, benzene and chloroform. It fuses at 130"-131 (366°-267°.8 P.), and boils at 300° (572° F.), suffering partial decomposition. It dissolves in concentrated HjSOi, and is decomposed by the acid when heated, but may be precipitated from the cold solution unchanged bydilution with HjO. Nitric acid does not affect it, even when heated. It is not attacked bj Br, by caustic alkalies or by nascent H. 

Tantalum and niobium are, like zirconium and titanium, reactive metals, that is, they rely on an oxide film for corrosion protection. The corrosion behavior of tantalum is similar to that of glass, that is, it can withstand most acids, but not hydrofluoric acid and caustic solutions. Tantalum is inert to nitric acid at all concentrations up to the boiling point and is resistant to hydrochloric acid at all concentrations up to 190 °C (Schussler and Pokross, 1987). There is only one commercially important tantalum alloy (Ta-2.5% W-0.15% Nb) which has corrosion resistance equivalent to that of tantalum (Hunkeler, 1997). When tantalum is coupled with other metals in any industrial application tantalum would generally become cathodic. When exposed to nascent hydrogen tantalum readily absorbs hydrogen and it is very sensitive to hydrogen embrittlement (HE) (Dillon, 1994). The corrosion behavior of niobium is similar to that... 

Cook JTE, Klein PG, Ward IM, Brain AA, Farrar DF, Rose J. The morphology of nascent and moulded ultra-high molecular weight polyethylene. Insights from solid-state NMR, nitric acid etching, GPC and DSC. Polymer 2000 41 8615. 

As an element, silicon is a hard brittle metallic-looking substance which crystallizes in the diamond lattice. It is produced commercially by the electrothermal reduction of silica, resulting in a product which contains about 97 per cent silicon. The element shows no visible oxidation or corrosion at ordinary temperatures and oxidizes very slowly below red heat. Halogens attack it more readily, and chlorination proceeds satisfactorily at 250° C. to form the silicon chlorides which are perhaps the best-known volatile compounds of silicon. Whenever the element is exposed to nascent hydrogen, or its metallic compounds are treated with acids, some hydrides usually are formed, as may be noticed by the odor which such hydrides impart to the gas evolved when cast iron is dissolved in dilute acids. A mixture of concentrated nitric and hydrofluoric acids will dissolve pure silicon, but mineral acids singly will not do so. Hot concentrated solutions of alkalies will dissolve it, however, with the evolution of hydrogen. 

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