Nitric acid concentrated acid and nitric oxide for dilute acid. or Concentrated nitric acid oxidizes I, P, and S into HIO, HPO, and HSO, respectively. Nitric acid reacts with proteins to form yellow nitrated products. This reaction is known as the xanthoproteic reaction. This test is carried out by adding concentrated nitric acid to the substance being tested, and then heating the mixture. If proteins that contain amino acids with aromatic rings are present, the mixture turns yellow. Upon adding a base such as ammonia, the color turns orange. These color changes are caused by nitrated aromatic rings in the protein. Xanthoproteic
Acid–base reaction these examples. For instance, carbon monoxide acts as a Lewis base when it forms an adduct with boron trifluoride, of formula FB←CO. Adducts involving metal ions are referred to as co-ordination compounds; each ligand donates a pair of electrons to the metal ion. The reaction can be seen as an acid–base reaction in which a stronger base (ammonia) replaces a weaker one (water) The Lewis and Brønsted–Lowry definitions are consistent with each other since the reaction is an acid–base reaction in both theories. One of the limitations of the Arrhenius definition is its reliance on water solutions. Edward Curtis Franklin