Ex. 1 Read and translate the text Nitric acid Nitric acid (HNO3) is a highly corrosive mineral acid. The pure compound is colorless. Commercially available nitric acid is an azeotrope. The boiling point of nitric acid is120.5 °C at 1 atm. The melting point of nitric acid is −42 °C (−44 °F; 231 K). Odour is acrid. Two solid hydrates are known; the monohydrate (HNO3·H2O) and the trihydrate (HNO3·3H2O). Chemists undergo nitric acid thermal decomposition: 4 HNO3 → 2 H2O + 4 NO2 + O2. This reaction gives rise to some non-negligible variations in the vapor pressure above the liquid because the nitrogen oxides which this reaction produces dissolve partly or completely in the acid. Nitric acid is the primary reagent for nitration. The nitration is the addition of a nitro group to an organic molecule. Nitric acid is normally a strong acid at ambient temperatures. Nitric acid is the powerful oxidizing agent. The concentration of available commercial nitric acid is 68 %. The density of concentrated nitric acid is 1.42 g/mL. Fuming nitric acid contains 90% of HNO3 and has a density of 1.50 g/mL.
We use this acid in the explosives industry. It is not as volatile and not as corrosive as the anhydrous acid and has the approximate concentration of 21.4 mole.
Red fuming nitric acid, or RFNA, contains substantial quantities of dissolved nitrogen dioxide (NO2). It leaves the solution with a reddish-brown color. Due to the dissolved nitrogen dioxide, the density of red fuming nitric acid is low.
Ex. 2 Answer the questions 1. What is nitric acid?
2. Is it an azeotrope?
3. What is the concentration of commercially available nitric acid?
4. Is it a primary reagent for nitration?
5. What do chemists undergo nitric acid ?
Ex. 3 Put the verbs in the brackets in the correct form in Present Simple. Nitric acid (to contain) ____ nitrogen oxide.
