Nitric acid (HNO) greatly enhance the rate of reaction. Although chromium (Cr), iron (Fe), and aluminium (Al) readily dissolve in dilute nitric acid, the concentrated acid forms a metal-oxide layer that protects the bulk of the metal from further oxidation. The formation of this protective layer is called passivation. Typical passivation concentrations range from 20% to 50% by volume (see ASTM A967-05). Metals that are passivated by concentrated nitric acid are iron, cobalt, chromium, nickel, and aluminium. Being a powerful oxidizing acid, nitric acid reacts violently with many organic materials and the reactions may be explosive. The hydroxyl group will typically strip
Acetoacetic acid colour change is graded by eye. The test does not measure β-hydroxybutyrate, the most abundant ketone in the body; during treatment of ketoacidosis β-hydroxybutyrate is converted to acetoacetate so the test is not useful after treatment begins and may be falsely low at diagnosis. Similar tests are used in dairy cows to test for ketosis. Acetoacetic acid Acetoacetic acid (also diacetic acid) is the organic compound with the formula CHCOCHCOOH. It is the simplest beta-keto acid group, and like other members of this class, it is unstable. The methyl and ethyl esters, which are quite stable, are produced on a