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–base titration Acid–base titration An acid–base titration is a method of quantitative analysis for determining the concentration of an acid or base by exactly neutralizing it with a standard solution of base or acid having known concentration. A pH indicator is used to monitor the progress of the acid–base reaction. If the acid dissociation constant (p"K"a) of the acid or base dissociation constant (P"K"b) of base in the analyte solution is known, its solution concentration (molarity) can be determined. Alternately, the p"K"a can be determined if the analyte solution has a known solution concentration by constructing a titration curve. Alkalimetry and acidimetry