Nitric acid copper, reaction with

The decomposition of the lower sulfides of the heavy metals and the recovery of the metal as soluble salts and of sulfur in the elemental form have been demonstrated for pyrite, pyrrhotite, chalcopyrite, sphalerite, galena, molybdenite, and associated metals such as nickel and cobalt. Pyrite and chalcopyrite are higher sulfides and to be amenable to this treatment have to be thermally decomposed at 600-650 C prior to leaching. The reactions with nitric acid are exothermic, and are carried out below 1 atm and at around 100°C. In addition to the sulfides, this technique has been applied successfully to the extraction of nonferrous metals from partly oxidized sulfide ores, fayalite slags, copper scrap, and other intermediate products, such as residue from electrolytic zinc plats. 

In Figure 2, you can see copper reacting with nitric acid. Again, several clues suggest that a chemical reaction is taking place. The color of the solution changes from colorless to blue. The solution bubbles and fizzes as a gas forms. The copper seems to be used up as the reaction continues. 

When copper reacts with nitric acid, several signs of a reaction are seen. A toxic, brown gas is produced, and the color of the solution changes. 

PIKRINSAEURE (German) (88-89-1) Flammable solid (flash point 302°F/150°C). Anhydrous material highly unstable and heat-, friction-, and impact-sensitive explosive (explodes at approximately 572°F/300°C). The presence of trace metals increases its sensitivity to explosion. Reaction with nitric acid, alkalis, heavy metals, copper, lead, zinc, transition metals, and other metals or their salts can produce other salts, known as picrates, that are initiators which are much more highly sensitive to heat, impact, or shock than this material. Mixtures with perchlorates form extremely powerful, high-velocity explosives. Shock-sensitive salts include ammonium salts and calcium salts the calcium salt may be produced... 

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). 

The reaction of copper with nitric acid should be done in a ventilation hood. Do not breathe the fumes from this reaction. 

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. 

Sodium Nitroprusside, Na2Fe(CN)5NO (22.6.7) It is synthesized by successive reactions including the reaction of potassium ferrocyanide with nitric acid, which forms potassium nitroprusside (22.6.5), which is further transformed to copper nitroprusside (22.6.6), and reaction of this with sodium carbonate gives sodium nitroprusside (22.6.7). 

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 ... 

As copper dissolves in the nitric acid, add new portions of copper shavings to it. When the entire selenium is oxidized, disconnect the flask with nitric acid, and suck a stream of dry air through the apparatus. Extract the prepared selenium(lV) oxide from the tube, put it into a weighing bottle, and weigh it. Determine the yield ip per cent. Write the equations of the reactions. Test the properties of selenium(IV) oxide (see p. 116). Hand in the preparation to your instructor. 

Pass a stream of hydrogen sulphide through the nitric acid in the fourth test tube. Write the equation of the reaction. Introduce a small amount of copper sulphide into the fifth tube with nitric acid. Explain why it dissolves in nitric acid. Write the equation of the reaction. 

---