Physical Properties of Nitric Acid Solutions

Table 1. Physical Properties of Nitric Acid Solutions at 20°C...

Nitric acid is a colourless liquid at room temperature and atmospheric pressure. It is soluble in water in all proportions and there is a release of heat of solution upon dilution. This solubility has tended to shape the process methods for commercial nitric acid manufacture. It is a strong acid that almost completely ionizes when in dilute solution. It is also a powerful oxidizing agent with the ability to passivate some metals such as iron and aluminium. A compilation of many of the physical and chemical properties of nitric acid is presented in Table A.1 of Appendix A. Arguably the most important physical property of nitric acid is its azeotropic point, this influences the techniques associated with strong acid production. The constant-boiling mixture occurs at 121.9°C, for a concentration of 68.4%(wt) acid at atmospheric pressure. 

Physical properties of hexachloroethane are Hsted in Table 11. Hexachloroethane is thermally cracked in the gaseous phase at 400—500°C to give tetrachloroethylene, carbon tetrachloride, and chlorine (140). The thermal decomposition may occur by means of radical-chain mechanism involving -C,C1 -C1, or CCl radicals. The decomposition is inhibited by traces of nitric oxide. Powdered 2inc reacts violentiy with hexachloroethane in alcohoHc solutions to give the metal chloride and tetrachloroethylene aluminum gives a less violent reaction (141). Hexachloroethane is unreactive with aqueous alkali and acid at moderate temperatures. However, when heated with soHd caustic above 200°C or with alcohoHc alkaHs at 100°C, decomposition to oxaHc acid takes place. 

Nitric acid solutions, physical properties of, 17 172t... 

Elemental composition Pb 64.11%, Cr 16.09%, O 19.80%. Lead chromate may be identified from its physical properties and x-ray crystallography. Lead and chromium can be measured in a nitric acid solution of the compound by AA, ICP, and other instrumental methods. (See Lead.)... 

Physical properties. Three crystalline forms of 1-chloro 2,4-dinitrobenzene are known. A stable a- modification (m. p. 53.4°C) crystallizes from nitric acid (62%) or from alcohol. An unstable, P- modification (m. p. 43 °C) can be precipitated, as Ostromyslenskii [11] reports, from a fuming nitric acid solution by treating it with water. It may also be obtained by rapid cooling of the molten substance. 

Pure nitric acid, a colorless liquid that readily fumes in moist air, is rarely encountered rather it is the concentrated aqueous solution of commerce with which most persons are familiar. A comparison of the physical properties of the pure acid versus the solution is made in the following tabulation ... 

Figure 8.1 Effect of pH on corrosion of 1100-H14 alloy (aluminum) by various chemical solutions. Observe the minimal corrosion in the pH range of 4-9. The low corrosion rates in acetic acid, nitric acid, and ammonium hydroxide demonstrate that the nature of the individual ions in solution is more important than the degree of acidity or alkalinity. (Courtesy of Alcoa Laboratories from Aluminum Properties and Physical Metallurgy, ed. John E. Hatch, American Society for Metals, Metals Park, Ohio, 1984, Figure 19, page 295.)...

Elemental composition Ni 78.58%, O 21.42%. Nickel may be analyzed in a diluted solution of the oxide in nitric acid by AA, ICP and other instrumental methods. The oxide may be identified from its physical properties and by x-ray diffraction. 

Elemental composition Sn 78.77%, 0 21.23%. Tin(IV) oxide can be identified by physical properties and x-ray diffraction. Tin content may be determined by various instrumental techniques in an acid solution of the oxide (See Tin). The compound is solubilized by digestion with nitric acid or aqua regia and diluted appropriately. 

The ultimate composition of ceria was established many years after its isolation by C, G, Mosander, a Swedish surgeon, chemist and mineralogist, who was for a time assistant to Berzelius, During the period 1839-1841, Mosander thermally decomposed a nitrate obtained from ceria and treated the product with dilute nitric acid. From the resulting solution, he then isolated first a new earth, "lanthana", and then another new earth, "didymia" (the twin brother of lanthana), of similar chemical but slightly different physical properties, (Figure 1)... 

The use of acid solutions (mainly hydrochloric, nitric, and sulfuric acids) offers quite high removal yields because metal ions tend to be more soluble at low pH values. A drawback is that the soil becomes acidified—this can introduce major alterations in its chemical, physical, and biological properties in addition, carbonate-rich soils strongly interact with the acids and produce CO2. As discussed in Chapter 3, metal complexes with natural or synthetic chelating agents tend to be soluble and stable. Then, heavy metals in soils can also be solubilized by chelation and extraction followed by an ex situ treatment. 

PHYSICAL PROPERTIES steel-gray, shiny, hard metal ductile somewhat malleable hydrated salts of cobalt are red soluble salts form red solutions which become blue on adding concentrated hydrochloric acid exists in two allotropic forms hexagonal form is more stable than the cubic form at room temperature readily soluble in dilute nitric acid insoluble in water magnetic ferromagnetic permeability two-thirds that of iron MP (1493°C, 2719°F) BP (3100°C, 5612°F) DN (8.92 g/cm at 20°C) SG (8.92) CP (0.1056 cal/g/°C at 15-100°C) LHV (1500cal/g) VP (0 mmHg at 68°F BHN (1.25). 

PHYSICAL PROPERTIES soft, bluish-gray metal highly lustrous when freshly cut very malleable easily melted, cast, rolled, and extruded tarnishes upon exposure to moist air cubic crystal structure poor conductor of electricity good sound and vibration absorber dissolve in dilute nitric acid soluble in hot concentrated sulfuric acid, acetic acid, and alkali solutions dissolves slowly in hydrogen chloride insoluble in hot or cold water MP (327.4°C, 621.3°F) BP (1740°C, 3164°F) DN (11.32 g/cm at20°C) SG (11.3) VS (3.2 cP at 327.4°C, 2.32 cP at 400°C, 1.54 cP at 600°C) (molten lead) CP (0.031 cal/g at 20°C) HV (206 cal/g at 1,740°C) VP (1.77 mmHg at 1000°C) BHN (4.0)(high purity lead) hardness 1 on Mohs scale. 

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