An Investigation of How Nitrogen Monoxide (NO) and Nitrogen Dioxide (NO_2) Are Produced in Oxidations by Nitric Acid (HNO3)

摘要

In oxidations by nitric acid (HNO_3), such as the dissolution of gold (Au) in aqua regia, mixtures of nitrogen monoxide (NO) and nitrogen dioxide (NO_2) are produced. In this article, the exact processes through which these two nitrogen oxides are produced were discussed. It was shown that in the processes of dissolution in HNO_3 or aqua regia, NO_2 is never a direct product of oxidations by HNO3. It was also explained that in such processes, NO_2 is always produced from HNO_3 and NO reacting. Further, the effect of the concentration of HNO_3 was discussed in light of thermodynamic calculations.