| Name | NITROUS ACID |
| Synonyms | HNO2 HONO NITROUS ACID kyselinadusite Kyselina dusite Nitrosyl hydroxide Nitrous acid, trans |
| CAS | 7782-77-6 |
| EINECS | 231-963-7 |
| Molecular Formula | HNO2 |
| Molar Mass | 47.01 |
| Density | 1.54±0.1 g/cm3(Predicted) |
| morphology | stable only in solution |
| acidity coefficient (pKa) | pK (25°) 3.35 |
| EPA chemical information | Nitrous acid (7782-77-6) |
| toxic substance data | 7782-77-6(Hazardous Substances Data) |
preparation method Ba(NO 2 ) 2 H 2 SO 4 & rarr;2HNO 2 BaSO 4
AgNO 2 HCl→HNO 2 AgCl↓
Under sufficient cooling with ice water, dissolve Ba(NO 2 ) 2 (or AgNO 2) in water and add dilute sulfuric acid (or dilute hydrochloric acid). Filtration removes the precipitated BaSO 4 (or AgCl) precipitate, and nitrous acid remains in the solution. If there is salt in the solution and it doesn't matter, acidify sodium nitrite with hydrochloric acid at a temperature below 0°C.