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
Acid perfusion test hoarseness, chronic cough, then 24 hr pH monitoring should be considered. Acid perfusion test Acid perfusion test, also called the Bernstein test, is a test done to reproduce the pain when the lower esophagus is irrigated with an acid solution in people with GERD (gastroesophageal reflux disease). There will be a negative result in normal people, but a false positive reading may be seen in up to 15% of people. Bernstein test is obsolete nowadays. 24 hour pH monitoring is the gold standard for GERD. However, the initial management is with proton pump inhibitors. If the patient does not respond