Nitric acid with copper

In a ventilation hood, place a piece of copper metal in a clean, dry evaporating dish. Add enough 6M nitric acid to cover the metal. CAUTION Nitric acid can cause burns. The reaction of nitric acid with copper generates dangerous fumes. Use a ventilation hood. 

Nitric oxide can be obtained conveniently in the laboratory by the reduction of nitric acid with copper, mercury, or iron(II) salts. 

Nitrogen monoxide (NO), commonly called nitric oxide, has been found to be an important regulator in biological systems. Nitric oxide is a colorless gas under normal conditions and can be produced in the laboratory by reacting 6 M nitric acid with copper metal ... 

The mixture of these gases may be made by adding nitric oxide to oxygen, or by reducing concentrated nitric acid with copper ... 

The method to be described uses cheap materials, is easy to carry out, and gives reasonably pure nitric oxide—purer than would be obtained by the reduction of dilute nitric acid with copper. 

Write a balanced net ionic equation for the reaction of nitric acid with insoluble copper(II) sulfide the products include Cu2+, S(s), and N02(g). 

Synthetic standard solution (for analysis of steel). Dissolve an appropriate weight of pure iron (Johnson Matthey) in a mixture of equal volumes of concentrated hydrochloric acid and concentrated nitric acid with this solution as base, add a suitable amount of copper nitrate solution containing 0.01 g copper per L. 

Copper oxide reacts with dilute sulfuric and nitric acids forming copper(II) sulfate and copper(II) nitrate, respectively, and precipitating metallic copper ... 

Nitric oxide also can be made by reactions of nitric acid, nitrate, or nitrite salts with metals, metal oxides, or sulfates. Several metals react with nitric acid liberating nitric oxide. (See Nitric Acid, Reactions). For example, action of 1 1 nitric acid on copper turnings forms nitric oxide ... 

OxideofOoba.lt, the ores of which, after grinding and roasting, to drive off as much as possible the excess of arsenic and sulphur, are dissolved in hydrochloric add, sometimes with the addition of a small quantity of nitric acid. The copper, lead, silver, arsenic, antimony, el cetera, are precipitated by sulphide of hydrogen, and to the filtered solution carbonate of lime is added in (he form of chalk, by which all the iron, alumina, and a trace ot cobalt are thrown down, the nickel and cobalt remaining in solution. To this solution which must ho hot and neutral, a solutien of bleaching powder is added in sufficient quantity to precipitate the cobalt, and the menstruum is then well boiled to remove the chlorine as fast as possible. The oxide of nickel is afterwards precipitated from the filtrate by the addition of hydrate of lime, and ebullition. 

Mesaconic acid has been prepared by heating citraconic acid with dilute nitric acid, with hydriodic acid,2 or with concentrated sodium hydroxide solution 3 by heating a concentrated water solution of itaconic or citraconic acid at 180-200° 4 by treating citradibromopyrotartaric acid and mesodibromopyrotartaric acid with potassium iodide and copper at 1500 5 and by heating citraconic anhydride with nitric acid.6... 

V. Sihvonen studied the electrolysis of nitric acid with platinum or copper cathodes, with a cathode of mercury in phosphoric or sulphuric acid at 25°-40° and also the electrolysis of hydroxylamine with the same cathodes. His idea of the mechanism of the reactions in the two cases is illustrated by ... 

J. Tafel found that while nitric acid is reduced only to hydroxylamine q.v.) by mercury or well-amalgamated electrodes, a copper cathode reduces it to ammonia and at the same time has no action on hydroxylamine. A. Brochet and J. Petit studied the electro-reduction of nitric acid by an alternating current. T. H. Jeffery described the electrolysis of nitric acid with a gold anode, and obtained from the anode liquor crystals of aurinitric acid, HAu(N03)4.3H20. R. Ihle s observations on the oxidation-potential of nitric acid have been discussed in connection with nitrous acid (q.v.). He found that if the cone, of the nitric acid be expressed by... 

Dilute nitric acid attacks copper, forming copper nitrate, a soluble salt, so that the surface of the metal remains free until the copper has all reacted. Copper oxide may be obtained by heating the solution, first to expel the water, and then with a somewhat stronger heat to decompose the residue of copper nitrate oxides of nitrogen escape as red fumes, and copper oxide remains as a black solid. This is the method by which zinc was converted quantitatively into zinc oxide, page 24. 

Nitric acid dissolves copper, forming cupric nitrate and oxides of nitrogen. The primary process corresponds with the equation... 

USAL has also been used in the determination of trace impurities in high-purity materials. This type of analysis is mandatory with a view to controlling their quality and studying the synergistic action of, and correlation with, impurities. The accuracy and precision of the analytical results depend strongly on the particular separation procedure used before the determination step, as shown in the multi-element quantitative USAL of impurities such as iron, copper, lead and bismuth in high-purity silver metal. For this purpose, a silver sample was dissolved in nitric acid and treated with chloride, after which the solution was evaporated to dryness and the impurities were redistributed on the surfaces or in the interstitial spaces of agglomerates of matrix crystals. Then, the impurities were leached into 0.1 M nitric acid with the aid of ultrasonic irradiation [91]. 

Oxidation of copper metal by nitric acid. The copper atoms lose two electrons to form Cu2+ ions, which give a deep green color that becomes turquoise when diluted with water. 

Another aspect of the advantage of bringing the depolarizer to the cathode is seen by comparing the results in Table LXXXV for smooth and spongy copper electrodes. The much larger effective area of the latter permits more intimate contact of the nitric acid with the cathode. It may be noted in this connection that in his extensive work on the electrolytic reduction of organic compounds, Tafel (1900) frequently used a prepared lead electrode, which had been roughened by electrolytic oxidation of the surface to lead dioxide followed by reduction to finely-divided lead by cathodic treatment. 

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