Nitrous Acid

HNO2, 47.013 g/mol. Its structure, the values that were measured, the values that were calculated, and where each one came from.

verified recordInorganic compound4 measured properties

Drawn from the SMILES. It shows how the atoms are connected — not a photograph of a molecule, and not its shape in space.

Identifiers

Molecular formula: HNO₂
Molecular weight: 47.013 g/mol
Exact mass: 47.000728 g/mol
IUPAC name: nitrous acid
SMILES: O=NO
InChI: InChI=1S/HNO2/c2-1-3/h(H,2,3)
InChIKey: IOVCWXUNBOPUCH-UHFFFAOYSA-N

Open in ReactionLens Use in reaction prediction

Both are open without an account.

Measured properties

Values somebody obtained from a sample and published. Where two sources report the same property they are both shown, in the units each used — a disagreement between them is information, and averaging it away would be inventing a number neither one gave.

Boiling Point: 320measured · DrugBank
Melting Point: 271measured · DrugBank
Solubility: 820g/Lmeasured · DrugBank
LogP: -3.7measured · DrugBank

Calculated properties

Derived from the structure rather than from a sample. These are reproducible and they are not measurements: a calculated partition coefficient and a measured one can differ by a long way, and where both exist they are listed apart on purpose.

Molecular weight: 47.014 g/molcalculated · reference compound database; Average mass of one molecule, from reference compound database.
Exact mass: 47.000728275 Dacalculated · reference compound database; Mass of the most common isotopic form.
XLogP3: -0.3calculated · reference compound database; Estimated oil/water partition, computed by reference compound database.
Polar surface area: 49.7 Å²calculated · reference compound database; Polar surface area as computed by reference compound database.
Complexity: 10calculated · reference compound database; A rough measure of how intricate the structure is.
H-bond donors: 1calculated · reference compound database
H-bond acceptors: 3calculated · reference compound database
logP: 0.142calculated · chemistry engine; Estimated preference for oil over water. Higher means more oil-like.
Topological polar surface area: 49.66 Å²calculated · chemistry engine; Surface area from polar atoms; relates to how easily a molecule crosses membranes.
H-bond donors: 1calculated · chemistry engine; Atoms that can donate a hydrogen bond.
H-bond acceptors: 2calculated · chemistry engine; Atoms that can accept a hydrogen bond.
Rotatable bonds: 0calculated · chemistry engine; Single bonds the molecule can freely twist around.
Molar refractivity: 7.5815 cm³/molcalculated · chemistry engine; Relates to the molecule's polarisability.
Fraction sp³ carbons: 0calculated · chemistry engine; Share of carbon atoms with tetrahedral bonding.
QED drug-likeness: 0.3119calculated · chemistry engine; Quantitative estimate of drug-likeness (0–1).

What it is made of

Elements

O Oxygen2 atoms · 68.1% by mass
N Nitrogen1 atom · 29.8% by mass
H Hydrogen1 atom · 2.1% by mass

Percentages are of the molecular weight above, worked out the same way the molar mass calculator does it.

Structure

Heavy atoms, hydrogen excluded: 3
Total atoms, hydrogen included: 4
Rings: 0
Aromatic rings: 0
Stereocentres: 0
Formal charge: 0

The molecule in three dimensions

Rotate and inspect the atoms. Loaded only when you ask, so the page stays light.

The drawing above is a diagram of what is bonded to what. A molecule is not flat, and the model here is one low-energy shape generated from the connectivity — useful for seeing which groups can reach each other, and not a measured structure. A real sample is a population of conformations, interconverting.

Reactions it appears in

No documented reaction with a written procedure and a source involves Nitrous Acid yet.

Other names for it

The systematic name on this record is nitrous acid.

The sources also call it Nitrosyl hydroxide, HNO2, Kyselina dusite, dioxonitric acid, hydroxidooxidonitrogen, Acid, Nitrous, T2I5UM75DN, hydrogen dioxonitrate(1-), DTXSID7064813, CHEBI:25567, (NO(OH)).

Structurally related

Nothing structurally close to Nitrous Acid has a page here yet.

Where these values came from

reference compound database24529
compound record
chemistry engine
structure perception

compound record.

What this page does not claim

The identifiers are what the source record holds, copied rather than recomputed. Measured values are reported as their source gave them, units and all; calculated values are marked as calculated and are not measurements. Where a field is absent the page says so, because a blank cell reads as a zero and a guessed value reads as a fact.

Nothing here is a hazard assessment, a purity statement or advice about handling a sample. A flash point quoted from a safety database is a number somebody published, not a judgement by us about whether this molecule is safe for what you intend.