Potassium nitrate

Athanor · official

KNO₃ · 101.103 g/mol

Also called saltpetre, nitre, E252

Inorganic

Open in Athanor

Drawn from its SMILES with RDKit

DangerMay intensify fire; oxidizer · Causes skin irritation · Causes serious eye irritation · May cause respiratory irritation

Names and identifiers

IUPAC name: potassium nitrate
Synonyms: saltpetre, nitre, E252
+ 37 more
Saltpeter, Nitre, Niter, Nitrate of potash, Vicknite, Nitric acid, potassium salt, Kaliumnitrat, Kalii nitras, Collo-Bo, Kali nitricum, Potassium nitrate(DOT), DTXSID4029692, Salt peter, RU45X2JN0Z, INS NO.252, INS-252, NSC-57632, DTXCID609692, E-252, CHEBI:63043, Schmidts, Sensitive Teeth, Sensitive Tooth Paste, RefChem:6673, Kiss My Face Sensitive, Dr. Sheffield Sensitive Care, Jason Total Protection Sensitive, SprinJene Natural Sensitivity and Gum, Schmidts WONDERMINT TOOTH AND MOUTH, Attitude Adult Fluoride-free-Sensitive-Spearmint, Kiss My Face Sensitive Fluoride-Free Whitening-Citrus Mint, 231-818-8, Nitric acid potassium salt, potassium;nitrate, KNO3, Salt peter (VAN), CHEMBL1644029
Molecular formula: KNO₃
Empirical formula: KNO₃
Molecular weight: 101.103 g/mol
Exact mass: 100.95152
CAS number: 7757-79-1
PubChem CID: 24434
Canonical SMILES: [N+](=O)([O-])[O-].[K+]
Isomeric SMILES: [N+](=O)([O-])[O-].[K+]
InChI: InChI=1S/K.NO3/c;2-1(3)4/q+1;-1
InChIKey: FGIUAXJPYTZDNR-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

TemperaturePressureDensity

Appearance: Potassium nitrate appears as a white to dirty gray crystalline solid. Water soluble. Noncombustible, but accelerates the burning of combustible materials. If large quantities are involved in fire or the combustible material is finely divided an explosion may result. May explode under prolonged exposure to heat or fire. Toxic oxides of nitrogen are produced in fires. Used in solid propellants, explosives, fertilizers.[1]
3 values
From CAMEO Chemicals, the most authoritative source here.
Value As written Source
–shown Potassium nitrate appears as a white to dirty gray crystalline solid. Water soluble. Noncombustible, but accelerates the burning of combustible materials. If large quantities are involved in fire or the combustible material is finely divided an explosion may result. May explode under prolonged exposure to heat or fire. Toxic oxides of nitrogen are produced in fires. Used in solid propellants, explosives, fertilizers. [1] CAMEO Chemicals
– Dry Powder; Large Crystals; Liquid; Dry Powder; Other Solid; Large Crystals; CBI [2] EPA Chemical Data Reporting (CDR)
– COLOURLESS-TO-WHITE CRYSTALLINE POWDER. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Odor: Odorless[4]
Melting point: 334.0 °C (633.2 °F, USCG 1999)[1]
3 values
3 of 3 sources agree on it (most common value).
Value As written Source
334.0 °Cshown 633.2 °F (USCG, 1999) [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
333 to 334 °C 333-334 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
334 °C 334 °C [5] PAC Chemical Database, U.S. Department of Energy
Boiling point: 400 °C (752 °F) at 760 mmHg (decomposes) (USCG, 1999)[1]
Density: 2.105 @25 °C[5]
3 values
3 of 3 sources agree on it (most common value).
Value As written Source
– 2.109 (USCG, 1999) - Denser than water [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
– 2.1 g/cm³ [3] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown 2.105 @25 °C [5] PAC Chemical Database, U.S. Department of Energy
Solubility in water: Solubility in water, g/100ml at 25 °C: 35.7[3]
3 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– Sol in water, glycerol; slightly sol in alcohol [4] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 14th Edition. John Wiley & Sons, Inc. New York, NY 2001., p. 915
– For more Solubility (Complete) data for POTASSIUM NITRATE (7 total), please visit the HSDB record page. [4] Hazardous Substances Data Bank (HSDB)
–shown Solubility in water, g/100ml at 25 °C: 35.7 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Refractive index: Index of refraction: 1.335 (Alpha), 1.5056 (Beta), 1.5064 (Gamma)[4]

Value	As written	Source
–shown	Potassium nitrate appears as a white to dirty gray crystalline solid. Water soluble. Noncombustible, but accelerates the burning of combustible materials. If large quantities are involved in fire or the combustible material is finely divided an explosion may result. May explode under prolonged exposure to heat or fire. Toxic oxides of nitrogen are produced in fires. Used in solid propellants, explosives, fertilizers.	[1] CAMEO Chemicals
–	Dry Powder; Large Crystals; Liquid; Dry Powder; Other Solid; Large Crystals; CBI	[2] EPA Chemical Data Reporting (CDR)
–	COLOURLESS-TO-WHITE CRYSTALLINE POWDER.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
334.0 °Cshown	633.2 °F (USCG, 1999)	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
333 to 334 °C	333-334 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
334 °C	334 °C	[5] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–	2.109 (USCG, 1999) - Denser than water	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
–	2.1 g/cm³	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown	2.105 @25 °C	[5] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–	Sol in water, glycerol; slightly sol in alcohol	[4] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 14th Edition. John Wiley & Sons, Inc. New York, NY 2001., p. 915
–	For more Solubility (Complete) data for POTASSIUM NITRATE (7 total), please visit the HSDB record page.	[4] Hazardous Substances Data Bank (HSDB)
–shown	Solubility in water, g/100ml at 25 °C: 35.7	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms: 5
Rings: 0
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0
H-bond donors: 0
H-bond acceptors: 3
Rotatable bonds: 0
TPSA (Å²): 66.2 computed here · PubChem 62.9
Formal charge: 0
Complexity: 18 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: D3h of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

K38.67%
N13.85%
O47.47%

Isotope pattern

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P: -3.24 Crippen (Wildman and Crippen 1999)
log S (water solubility): 1.57 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.32 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 101.1
log P ≤ 5 (Crippen): -3.24
H-bond donors ≤ 5: 0
H-bond acceptors ≤ 10: 3

Passes all four rules.

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Danger

Most widely reported: 2,229 company reports to ECHA. Source [6].

Oxidizer
Harmful or irritant

H272May intensify fire; oxidizer (93.9% of reports)
H315Causes skin irritation (59.4% of reports)
H319Causes serious eye irritation (59.5% of reports)
H335May cause respiratory irritation (59.3% of reports)

Precautionary statements: P210, P220, P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P319, P321, P332+P317, P337+P317, P362+P364, P370+P378, P403+P233, P405, P501

View all classifications (2)

[6] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 5.9% (131 of 2229) of reports.
[6] European Chemicals Agency (ECHA) · 2,229 reports · DangerH272, H315, H319, H335

First aid

Get medical attention. Inhalation: Remove to fresh air. Eyes: Flush with water for at least 15 min., lifting lids occasionally. Skin: Remove contaminated clothing and shoes. Flush with water. (USCG, 1999)[1]
General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[7]
Fresh air, rest. Refer for medical attention.[3]
Remove contaminated clothes. Rinse and then wash skin with water and soap.[3]

Storage

Separated from combustible substances and reducing agents.[3]
Separated from combustible and reducing substances.[4]

Incompatibilities

A micro Parr calorimeter exploded when the wrong proportions of these ingredients were used. The intended mixture was 4.0 g sodium peroxide, 0.2 g dextrose, and 0.2 g potassium nitrate; actual proportions were 0.35 g, 2.59 g, and 0.2 g respectively. There was insufficient sodium peroxide to dissolve decomposition gases, hence a rapid temp and pressure build-up caused the Parr bomv to burst.[4]
... A mixture of potassium nitrate and sodium hypophosphite constitutes a powerful explosive.[4]
A mixture of arsenic and potassium nitrate explodes when ignited.[4]
A batch of 3,257 g of boron, 9362 g of potassium nitrate, 989 g of laminac, and 500 g of trichloroethylene had been mixing for 5 min, when an explosion occurred.[4]

Safety data sheets on the supplier’s page: Sigma-Aldrich, Thermo Fisher Scientific, Angene Chemical.

Always read the supplier’s safety data sheet before working with it.

Spectra

GC-MSSpectraBase (GC/MS)
FTIRSpectraBase (KBr pellet)
ATR-IRSpectraBase
RamanRRUFF Project · RRUFF Project · RRUFF Project · SpectraBase (Bio-Rad FTS 175C with Raman accessory · FT-Raman)

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

[1]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
[2]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
[3]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[4]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[5]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
[6]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[7]Emergency Response Guidebook (ERG) · Public domain (US DOT) · via PubChem · retrieved 2026-10-14
[8]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[9]RRUFF Project · Linked only · via PubChem · retrieved 2026-10-14
·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
·Literature on PubChem

Data last updated 2026-10-14.