1. The nitrite ion has the chemical formula NO−2. Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name nitrite also refers to organic compounds having the –ONO group, which are esters of nitrous acid. == Production == Sodium nitrite is made industrially by passing a mixture of nitrogen oxides into aqueous sodium hydroxide or sodium carbonate solution: NO + NO2 + 2 NaOH → 2 NaNO2 + H2O NO + NO2 + Na2CO3 → 2 NaNO2 + CO2 The product is purified by recrystallization. Alkali metal nitrites are thermally stable up to and beyond their melting point (441 °C (826 °F) for KNO2). Ammonium nitrite can be made from dinitrogen trioxide, N2O3, which is formally the anhydride of nitrous acid: 2 NH3 + H2O + N2O3 → 2 NH4NO2 == Structure == The nitrite ion has a symmetrical structure (C2v) symmetry), with both N–O bonds having equal length and a bond angle of about 115... from wikipedia.org