Nitric acid Nitric acid can oxidize non-active metals such as copper and silver. With these non-active or less electropositive metals the products depend on temperature and the acid concentration. For example, copper reacts with dilute nitric acid at ambient temperatures with a 3:8 stoichiometry: The nitric oxide produced may react with atmospheric oxygen to give nitrogen dioxide. With more concentrated nitric acid, nitrogen dioxide is produced directly in a reaction with 1:4 stoichiometry: Upon reaction with nitric acid, most metals give the corresponding nitrates. Some metalloids and metals give the oxides; for instance, Sn, As, Sb, and Ti are oxidized into SnO,
Phosphorous acid concentrating the solution and precipitations with alcohols, the pure acid can be separated from the salt. Phosphorous acid is a strong acid with a p"K" in the range 1.26–1.3. It is a diprotic acid, the hydrogenphosphite ion, HP(O)(OH) is a moderately strong acid: The conjugate base HP(O)(OH) is called hydrogen phosphite, and the second conjugate base, , is the phosphite ion. (Note that the IUPAC recommendations are hydrogen phosphonate and phosphonate respectively). The hydrogen atom bonded directly to the phosphorus atom is not readily ionizable. Chemistry examinations often test students' appreciation of the fact that "not" all three hydrogen atoms