Asam nitrat: Perbedaan antara revisi

 

Asam nitrat dibuat dengan mencampur [[nitrogen dioksida]] ([[Nitrogen|N]][[Oksigen|O]]₂) dengan [[air]]. Menghasilkan asam nitrat yang sangat murni biasanya melibatkan distilasi dengan [[asam sulfat]], karena asam nitrat membentuk sebuah [[azeotrop]] dengan air dengan komposisi 68% asam nitrat dan 32% air. Asam nitrat kualitas komersial biasanya memiliki konsentrasi antara 52% dan 68% asam nitrat. Produksi komersial dari asam nitrat melalui [[proses Ostwald]] yang ditemukan oleh [[Wilhelm Ostwald]].

 

The dissolved [[NOx|NO_x]] are readily removed using reduced pressure at room temperature (10-30 min at 200 [[torr|mmHg]] or 27 [[kilopascal|kPa]]). Obtained white fuming nitric acid has density 1.51 g/cm³. This procedure can also be performed under reduced pressure and temperature in one step in order to produce less [[nitrogen dioxide]] gas.

 

White fuming nitric acid, also called 100% nitric acid or WFNA, is very close to the anhydrous nitric acid product. One specification for white fuming nitric acid is that it has a maximum of 2 % water and a maximum of 0.5 % dissolved NO₂. Red fuming nitric acid, or RFNA, contains substantial quantities of dissolved nitrogen dioxide (NO₂) leaving the solution with a reddish-brown color. One formulation of RFNA specifies a minimum of 17% NO₂, another specifies 13% NO₂. In either event, an ''inhibited'' fuming nitric acid (either IWFNA, or IRFNA) can be made by the addition of 0.6 to 0.7% [[hydrofluoric acid|hydrogen fluoride]], HF. This fluoride is added for corrosion resistance in metal tanks (the fluoride creates a metal fluoride layer that protects the metal).

 

It has additional uses in [[metallurgy]] and [[refining]] as it reacts with most [[metal]]s, and in [[chemical synthesis|organic syntheses]]. When combined with [[hydrochloric acid]], it forms [[aqua regia]], one of the few reagents capable of dissolving [[gold]] and [[platinum]].