Nitric acid aqua regia

Technetium is a silvery-gray metal that tarnishes slowly in moist air. The common oxidation states of technetium are +7, +5, and +4. Under oxidizing conditions technetium (Vll) will exist as the pertechnetate ion, TcOr-. The chemistry of technetium is said to be similar to that of rhenium. Technetium dissolves in nitric acid, aqua regia, and cone, sulfuric acid, but is not soluble in hydrochloric acid of any strength. The element is a remarkable corrosion inhibitor for steel. The metal is an excellent superconductor at IIK and below. 

Several common acid treatments for sample decomposition include the use of concentrated nitric acid, aqua regia, nitric—sulfuric acids, and nitric perchloric acids. Perchloric acid is an effective oxidant, but its use is ha2ardous and requkes great care. Addition of potassium chlorate with nitric acid also assists in dissolving any carbonaceous matter. 

Titanium carbide is resistant to aqueous alkaU except in the presence of oxidising agents. It is resistant to acids except nitric acid, aqua regia, and mixtures of nitric acid with sulfuric or hydrofluoric acid. In oxygen at 450°C, a nonprotecting anatase coating forms. The reaction... 

A bright white metal soft and ductile body-centered cubic structure index of refraction 3.03 density 5.96 g/cm melts at 1,910°C vaporizes at 3,407°C electrical resistivity, 18.1 microhm-cm at 0°C and 20.1 microhm-cm at 25°C magnetic susceptibility 1.4x10 cgs units modulus of elasticity 18-19x10 psi shear modulus 6.73xl0 psi Poisson s ratio 0.36 thermal neutron absorption cross section 5 barns/atom insoluble in water, dilute sulfuric acid, and hydrochloric acid at all concentrations soluble in nitric acid, aqua regia, and concentrated sulfuric acid insoluble in alkalies. 

Copper and silver will dissolve in nitric acid or hot sulfuric acid. A mixture of hydrochloric and nitric acids (aqua regia) will dissolve gold. It has recently been reported lhat mixtures of halngcns and quaternary ammonium halides in organic solvents dissolve gold faster ihan does aqua regia, see Nakao, Y. J. Chem. Soc. Chem. Ccmmun. 1992. 426-427. 

The conditions under which the formation of the arsenides Fe3As and Fe5As4 may occur are indicated on p. 65. The former was obtained by Brakl 1 as a black precipitate by the action of arsine on an alcoholic solution of ferrous ammonium sulphate. The product was only slightly attacked by concentrated hydrochloric or sulphuric acid but was soluble in nitric acid, aqua regia and bromine water. 

Chromic sulphide is a broAvnish-black, lustrous amorphous powder, of density 3-538 at 14° C. When heated in air it gives sulphur dioxide and chromium sesquioxide, Avhile in hydrogen it yields chromous sulphide. It is attacked and oxidised by nitric acid, aqua regia, and fused potassium nitrate. Compounds of chromic sulphide with sulphides of other metals haA-e been described. Regarding chromic sulphide as the thioanhydride of thiochromous acid, H2Cr2S4, these compounds may be described as thiochromites. 

Derivation By heating powdered osmium in air, or by treating it with nitric acid, aqua regia, or chlorine. 

Light gray or white lustrous powder, fused hard lumps or body-centered cubic crystals not tarnished in air and not appreciably affected by moisture at ordinary temp, mp 1917°. d18 6.11. Sp heat (20-100°) 0.]2 cal/g/°C. Electrical resistivity 24.8 microhms/cm. Inso] in water. Not attacked by hot or cold hydrochloric add, by cold sulfuric acid. Reacts with hot sulfuric acid, hydrofluoric acid, nitric acid, aqua regia. Not attacked by bromine water, or by aq alkalies. The metal precipitates gold, silver and platinum from their salts reduces mercuric salts to mercurous, ferric salts to ferrous,... 

Besides the classical nitric acid treatments, other oxidative agents have been used to prepare functionalized CNTs. Rao et al. [170] have compared the effects of concentrated nitric acid, aqua regia, HF-BF3, aqueous OSO4, and KMn04 (acid/alkali) solutions on MWCNT structures [170]. Indeed, all these oxidants... 

About 5% of the Ga dissolves during purification. Although a mixture of hydrochloric and nitric acids (aqua regia) is not used, the Ga is spectroscopically free of Pt (and also of Pb and SiO after the treatment. 

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