Nitric acid gold purity. Being a powerful oxidizing agent, nitric acid reacts violently with many non-metallic compounds, and the reactions may be explosive. Depending on the acid concentration, temperature and the reducing agent involved, the end products can be variable. Reaction takes place with all metals except the noble metals series and certain alloys. As a general rule, oxidizing reactions occur primarily with the concentrated acid, favoring the formation of nitrogen dioxide (NO). However, the powerful oxidizing properties of nitric acid are thermodynamic in nature, but sometimes its oxidation reactions are rather kinetically non-favored. The presence of small amounts of nitrous acid
Acid-base extraction Acid-base extraction Acid-base extraction is a procedure using sequential liquid–liquid extractions to purify acids and bases from mixtures based on their chemical properties. Acid-base extraction is routinely performed during the work-up after chemical syntheses and for the isolation of compounds and natural products like alkaloids from crude extracts. The product is largely free of neutral and acidic or basic impurities. It is not possible to separate chemically similar acids or bases using this simple method. The fundamental theory behind this technique is that salts, which are ionic, tend to be water-soluble while neutral molecules tend not to be. The addition