170135_inorganicventures_flipping

11:6 Acid Digestions of Inorganic Samples

Nitric Acid Diges-ons: Facts about nitric acid (cont)

§ The most common 'good ligands' used in combina5on with nitric acid are HCl, HF, and tartaric acid (for Sb). If nitric acid was a be@er ligand, these addi5onal acids would not be needed. § Concentra5ons of HNO3 between 65% and 69% are known as 'concentrated'; concentra5ons greater than 69.2% are known as 'fuming nitric acid'. § 100% nitric acid is light and heat sensi5ve and boils at 84 ̍C. ‘Concentrated' nitric acid boils as an azeotrope (with water at 69.2% HNO3) at a temperature of 121.8 ̍C. The dis5lled HNO3 (trace metals grade) should be at the 69.2% concentra5on level.

11:7 Acid Diges-ons of Inorganic Samples

Nitric Acid Diges-ons: Facts about nitric acid (cont)

§ Check with your manufacturer of doubly dis8lled nitric acid to determine if the container in which it is packaged is nitric acid leached prior to use. In the case of Teflon containers, the container material is generally assumed to be pure. § PTFE and PFA Teflon can be heated with concentrated nitric acid, even at high pressures or with combina8ons such as nitric + HCl, nitric + HF, and nitric + H2O2. § Nitric acid is not a strong enough oxidizing agent by itself to convert organic molecules to CO2↑ and H2O (completely oxidize).