☣️ UN 2508 • CLASS 8
UN 2508 — Molybdenum pentachloride
Placard: Corrosive. ERG Guide 156. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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UN 2508 Quick Details
UN 2508
Product name: Molybdenum pentachloride
DOT Class: 8
Placard type: Corrosive
ERG Guide: 156 (check current ERG)
Initial isolation: ERG 156: isolate spill 25m all directions; if fire or large spill, isolate 800m and evacuate downwind areas
Common Hazards of UN 2508
- Combustible material: may burn but does not ignite readily.
- Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
- When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
- Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
- Vapors may travel to source of ignition and flash back.
- Corrosives in contact with metals may evolve flammable hydrogen gas.
- Containers may explode when heated or if contaminated with water.
- TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
Chemical Identity & Physical Properties
| Also known as | Molybdenum(V) chlorideMolybdenum chloridePentachloromolybdenum |
| CAS Number | 10241-05-1 |
| Appearance | Dark green to black crystalline solid with a pungent, irritating odor. Hygroscopic and fumes in moist air. |
| Flash Point | Not applicable (non-flammable solid, but combustible) |
| Boiling Point | 268C (514F) with decomposition |
| Vapor Density | Not applicable (solid, but vapors heavier than air when heated) |
| Water Reactivity | Reacts violently with water, releasing corrosive and toxic hydrogen chloride gas and heat |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2508
Extinguishing Media
Dry chemical, soda ash, lime, sand; do NOT use water or foam
PPE Requirements
⚠️ Level B minimum; full face SCBA required; acid-resistant suit and gloves mandatory
Isolation & Evacuation
ERG 156: isolate spill 25m all directions; if fire or large spill, isolate 800m and evacuate downwind areas
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 156).
First Actions for a UN 2508 Incident
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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📋 Copy & Share Field Card
UN 2508 — Molybdenum pentachlorideHAZMAT RADIO NOTE — UN 2508
Product: Molybdenum pentachloride
Class 8 / Corrosive / ERG 156
PPE: Level B minimum; full face SCBA required; acid-resistant suit and gloves mandatory
ISOLATION: ERG 156: isolate spill 25m all directions; if fire or large spill, isolate 800m and evacuate downwind areas
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 2508 — Molybdenum pentachloride
Class: 8 | Placard: Corrosive | ERG Guide: 156
Appearance: Dark green to black crystalline solid with a pungent, irritating odor. Hygroscopic and fumes in moist air.
Water Reactivity: Reacts violently with water, releasing corrosive and toxic hydrogen chloride gas and heat
Extinguishing: Dry chemical, soda ash, lime, sand; do NOT use water or foam
PPE: Level B minimum; full face SCBA required; acid-resistant suit and gloves mandatory
Isolation: ERG 156: isolate spill 25m all directions; if fire or large spill, isolate 800m and evacuate downwind areas
— Key Hazards —
• Combustible material: may burn but does not ignite readily.
• Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
• When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/2508 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2508 Molybdenum pentachloride Cls8 ERG156 | allfirefighter.com/hazmat/un/2508SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/2508
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Frequently Asked Questions about UN 2508
Combustible material: may burn but does not ignite readily. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas Vapors may travel to source of ignition and flash back. Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water. TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level B minimum; full face SCBA required; acid-resistant suit and gloves mandatory
Water reactivity: Reacts violently with water, releasing corrosive and toxic hydrogen chloride gas and heat. Recommended extinguishing: Dry chemical, soda ash, lime, sand; do NOT use water or foam.
ERG Guide 156 recommendation: ERG 156: isolate spill 25m all directions; if fire or large spill, isolate 800m and evacuate downwind areas
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 156 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.