Substance profile
Arsenic pentoxide
Arsenic pentoxide is a white amorphous powder.
01 · Identification
What Arsenic pentoxide is
Arsenic pentoxide is a white amorphous powder. It boils at 160 °C, melts at 315 °C.
Under the GHS it carries the signal word Danger. It is classed as carcinogens.
02 · Identifiers
Arsenic pentoxide identifiers and molecular data
Arsenic pentoxide CAS number and EC number
Arsenic pentoxide molecular formula and molecular weight
Other names for Arsenic pentoxide
- diarsenic pentaoxide
- arsenic oxide
03 · GHS classification
Arsenic pentoxide hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Arsenic pentoxide pictograms and signal word
Arsenic pentoxide hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 3 | H301 | GHS06 |
| Acute toxicity - inhalation GHS chapter 3.1 | Category 3 | H331 | GHS06 |
| Carcinogenicity GHS chapter 3.6 | Category 1A or 1B | H350 | GHS08 |
| Hazardous to the aquatic environment - acute GHS chapter 4.1 | Category 1 | H400 | GHS09 |
| Hazardous to the aquatic environment - chronic GHS chapter 4.1 | Category 1 | H410 | GHS09 |
Where two values are shown with “or”, the hazard statement is shared by more than one category or by more than one class, and the code alone does not say which. H272, for example, belongs to oxidising liquids and to oxidising solids — the physical state decides. The binding answer for a specific entry is in the CLP Annex VI table itself.
Arsenic pentoxide hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H350 | May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. |
| H331 | Toxic if inhaled. |
| H301 | Toxic if swallowed. |
| H400 | Very toxic to aquatic life. |
| H410 | Very toxic to aquatic life with long lasting effects. |
This page lists only the codes assigned to Arsenic pentoxide. The full reference lives on the hazard statements hub, the precautionary statements hub and the GHS pictograms hub.
Safety Data Sheet
Getting an SDS for Arsenic pentoxide
A Safety Data Sheet is written for a product, not for a substance: the supplier of the grade you actually buy issues it, so two suppliers of Arsenic pentoxide issue two different sheets. That is why there is no single authoritative SDS for a substance to download — what there is, is the job of collecting the sheets for the products you hold and keeping them current as suppliers revise them.
04 · Precautionary statements
Arsenic pentoxide precautionary statements
CLP Annex VI assigns 14 precautionary statements to Arsenic pentoxide. They are grouped the way a label groups them: what to do before handling, what to do when something has already happened, how to store it and how to dispose of it.
Prevention
What to do before and during handling so the hazard never happens.
Response
What to do once exposure, spillage or fire has already happened.
Disposal
What has to happen to the contents and the empty container.
Reading the notation. … is a blank the supplier fills in — not a truncated sentence.· [square brackets] mark a part printed only when it applies.
05 · Names in the regulation
Arsenic pentoxide name in 23 EU languages
CLP Annex VI Part 3 is published in every language edition of the regulation, and the identification column is written out in each of them. Nothing below is translated by us: each line is the name as that edition prints it. Under Art. 18(2) the substance name from Annex VI is a lawful product identifier, so this is the wording to put on a label going to that market — and where the cell lists several designations, any one of them qualifies.
| Language | Name in CLP Annex VI Part 3 |
|---|---|
| Bulgarian български | диарсенов пентаоксид арсенов пентаоксидарсенов оксид |
| Spanish español | Pentaóxido de diarsénico pentaóxido de arsénicoóxido de arsénico |
| Czech čeština | oxid arseničný |
| Danish dansk | diarsenpentaoxid arsenpentaoxidarsenoxid |
| German Deutsch | Diarsenpentaoxid Arsenpentaoxid |
| Estonian eesti | diarseenpentaoksiid arseenpentoksiidarseenoksiid |
| Greek ελληνικά | πεντοξείδιο του διαρσενικού πεντοξείδιο του αρσενικούοξείδιο του αρσενικού |
| English English | diarsenic pentaoxide arsenic pentoxidearsenic oxide |
| French français | pentaoxyde de diarsenic pentoxyde d'arsenicoxyde d'arsenic |
| Croatian hrvatski | diarsenov pentaoksid arsenov pentoksidarsenov oksid |
| Italian italiano | pentaossido di diarsenico pentaossido di arsenicoossido di arsenico |
| Latvian latviešu | diarsēna pentaoksīds arsēna pentoksīdsarsēna oksīds |
| Lithuanian lietuvių | diarseno pentoksidas arseno pentoksidasarseno oksidas |
| Hungarian magyar | diarzén-pentoxid arzén-pentoxidarzén-oxid |
| Maltese Malti | pentaossidu tad-diarseniku pentossidu tal-arsenikuossidu tal-arseniku |
| Dutch Nederlands | diarseenpentaoxide arseenpentaoxidearseenoxide |
| Polish polski | pentatlenek arsenu tlenek arsenu(V)tlenek arsenowy |
| Portuguese português | pentóxido de diarsénio pentóxido de arsénioóxido arsénico |
| Romanian română | pentaoxid de diarsen pentoxid de arsenoxid de arsen |
| Slovak slovenčina | oxid arzeničný |
| Slovenian slovenščina | diarzenov pentaoksid arzenov pentoksidarzenov oksid |
| Finnish suomi | diarseenipentoksidi arseenipentoksidi |
| Swedish svenska | diarsenikpentaoxid arsenikpentoxidarsenikoxid |
All 23 language editions of Annex VI carry this entry. Irish is the twenty-fourth official EU language and has no line here for a different reason: no consolidated CLP text has ever been published in Irish, so there is no Irish edition of Annex VI to quote a name from. Source: consolidated CLP, CELEX 02008R1272, language editions. © European Union, https://eur-lex.europa.eu — only the electronic Official Journal of the European Union is authentic.
06 · Label elements
Arsenic pentoxide GHS label elements
Everything CLP Annex VI fixes for Arsenic pentoxide, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Arsenic pentoxide
- May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- Toxic if inhaled.
- Toxic if swallowed.
- Very toxic to aquatic life.
- Very toxic to aquatic life with long lasting effects.
- Obtain special instructions before use.
- Do not breathe dust/fume/gas/mist/vapours/spray.
- Do not eat, drink or smoke when using this product.
- Use only outdoors or in a well-ventilated area.
- Avoid release to the environment.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF INHALED:
- IF exposed or concerned:
- Immediately call a POISON CENTER/doctor/…
- Get medical advice/attention.
- Rinse mouth.
- Collect spillage.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Arsenic pentoxide in the GHS label constructor →
07 · Health hazards
Arsenic pentoxide health hazards and exposure limits
Arsenic pentoxide hazard summary
A skin, eye, and respiratory tract irritant; May cause arsenic poisoning; [ICSC] May cause skin sensitization; [HSDB] Extremely toxic with an oral lethal dose for humans of 5-50 mg/kg, or between 7 drops and 1 teaspoonful for a 150-lb. person; [CAMEO] An irritant; [MSDSonline] See Arsenic and the linked occupational diseases.
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
Arsenic pentoxide carcinogenicity classification
Classification of carcinogenicity: 1) evidence in humans: sufficient; 2) evidence in animals: limited. Overall summary evaluation of carcinogenic risk to humans is Group 1: Carcinogenic to humans. NOTE: This evaluation applies to the group of chemicals as a whole and not necessarily to all individual chemicals within the group. /Arsenic and arsenic compounds/
Source: Hazardous Substances Data Bank (HSDB)
Cancer Classification: Group A Human Carcinogen
Source: Hazardous Substances Data Bank (HSDB)
An IARC group and a CLP classification answer different questions. IARC judges whether the evidence for cancer in humans is strong enough; CLP Annex VI is the legally binding EU classification. A substance can carry one and not the other.
Arsenic pentoxide occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 0.01 [mg/m3], as As | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 5 mg As/m3 ; A potential occupational carcinogen. (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 5.0 [mg/m3], as As | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 5 mg/cu m (as As); NIOSH considers arsenic (inorganic compounds, as As) to be a potential occupational carcinogen. /Arsenic (inorganic compounds, as As)/ | Hazardous Substances Data Bank (HSDB) |
These are United States values. The European Union sets its own indicative and binding limits, and the figure that applies at a given workplace is the one in the local regulation — not the one shown here.
08 · Physical and chemical properties
Arsenic pentoxide properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
Arsenic pentoxide boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 160 °C (320 °F) | Hemihydrate | HSDB |
Arsenic pentoxide melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 315 °C (599 °F) | HSDB |
Arsenic pentoxide density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 4.32 g/cm³ | HSDB | |
| 4.3 g/cm³ | ICSC |
Arsenic pentoxide solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Freely soluble in water or alcohol | HSDB | |
| Very soluble in ethanol | HSDB | ||
| In water, 65.8 g/100 g at 20 °C | at 20 °C | HSDB |
Arsenic pentoxide flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | Not flammable (EPA, 1998) | CAMEO |
Arsenic pentoxide lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | Containers may explode when heated | HSDB |
Arsenic pentoxide corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | Corrosive to metals in the presence of moisture. | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Arsenic pentoxide fire and explosion behaviour
These are descriptions rather than measured values, so they are kept out of the table above and quoted here with the source that reported them.
Arsenic pentoxide fire potential
Not combustible, but if involved in a fire decomposes to produce fumes of arsenic.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Arsenic pentoxide storage and handling
Arsenic pentoxide safe storage
Separated from strong bases, reducing agents and food and feedstuffs. Dry. Well closed.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Arsenic pentoxide storage conditions
Store in tightly-closed containers in a cool, well-ventilated area away from metals, acids and other incompatible materials.
Source: Hazardous Substances Data Bank (HSDB)
Arsenic pentoxide incompatible materials
With bromine pentafluoride: Contact with arsenic pentoxide at ambient or slightly elevated temperatures is violent, ignition often occurring.
Source: Hazardous Substances Data Bank (HSDB)
Planning storage for a mix of chemicals? Check Arsenic pentoxide in the storage compatibility matrix →
11 · Transport
Arsenic pentoxide UN number and transport classification
Transport classification is a separate system from the GHS classification above. It decides how a package is marked and how a load may be carried; it does not follow from the workplace label, and the workplace label does not follow from it. The entries below are linked by CAS number, never by name.
Arsenic pentoxide under UN 1559 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| ARSENIC PENTOXIDE | 6.1 | T5 | II | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 6.1 is “Toxic substances” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Arsenic pentoxide | 6.1 | II | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 6.1 is “Poisonous materials” (49 CFR 173.2).
12 · Questions
Arsenic pentoxide — frequently asked questions
What is the CAS number of Arsenic pentoxide?
The CAS number of Arsenic pentoxide is 1303-28-2. Its EC number is 215-116-9.
What does a Arsenic pentoxide label have to show?
Under CLP Annex VI the label for Arsenic pentoxide carries the pictograms Skull and crossbones, Health hazard and Environment and the signal word is Danger.
Is Arsenic pentoxide flammable?
CLP Annex VI assigns Arsenic pentoxide no flammability hazard class. That is not a statement that it cannot burn: the harmonised list only records the hazards that were assessed for it. The flash point reported for it is Not flammable (EPA, 1998) (CAMEO).
Is Arsenic pentoxide a carcinogen?
Yes. CLP Annex VI classifies Arsenic pentoxide as a category 1A or 1B carcinogen and assigns it H350: may cause cancer.
What is the exposure limit for Arsenic pentoxide?
The US occupational exposure limit reported for Arsenic pentoxide is 0.01 [mg/m3], as As (Haz-Map, Information on Hazardous Chemicals and Occupational Diseases). Limits differ by country: the EU sets its own indicative and binding values, and the figure that applies at a given workplace is the one in the local regulation.
What is the boiling point of Arsenic pentoxide?
The boiling point reported for Arsenic pentoxide is 160 °C (320 °F), Hemihydrate (HSDB).
What is the melting point of Arsenic pentoxide?
The melting point reported for Arsenic pentoxide is 315 °C (599 °F) (HSDB).
How should Arsenic pentoxide be stored?
Store in tightly-closed containers in a cool, well-ventilated area away from metals, acids and other incompatible materials. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Arsenic pentoxide
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