UN/NA Number Reference
DOT Class 8 Corrosive placard

UN 2949: Sodium hydrosulfide, hydrated

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 2949 is assigned the proper shipping name Sodium hydrosulfide, hydrated in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 8 Corrosive material, Packing Group II. Required label(s): 8.

Packing group indicates the degree of danger within a hazard class: PG I is high danger, PG II medium, PG III low. The proper shipping name, hazard class, UN number, and packing group together form the basic shipping description that must appear on shipping papers and, where required, on the package and placard.

Emergency Response (ERG Guide 153)

Hazards: TOXIC. Combustible. Corrosive. Causes burns. Toxic fumes when heated.

Fire: Small: dry chemical, CO2, water spray. Large: water spray, foam.

Spill: Do not touch. Stop leak if safe. Use water spray to reduce vapor.

Chemical and Physical Properties

Sodium hydrosulfide is a colorless to light yellow crystalline solid or fused mass. It is corrosive to skin and metal. Used in paper pulping, manufacturing dyes, and dehairing hides.

CAS Number: 16721-80-5
Molecular Formula: HNaS
Molecular Weight: 56.07 g/mol
Color / Form: Rhombohedric-cubic crystals. White to colorless.
Odor: ODOR OF HYDROGEN SULFIDE
Boiling Point: 212 F
Melting Point: 63 °F (USCG, 1999)
Specific Gravity: 1.3 (sinks in water)
Vapor Pressure: 49.12 mmHg
Water Solubility: SOL IN WATER, ALCOHOL, ETHER
Log P: -3.5

Regulatory Data

CERCLA RQ (40 CFR 302.4)
5000 lb

A release of this material at or above its CERCLA reportable quantity (5000 lb) requires immediate notification to the National Response Center at 800-424-8802.

Special Provisions

49 CFR 172.102 special provision codes for this entry: A7, IB8, IP2, IP4, T7, TP2. These codes modify the general requirements (packaging, quantity limits, exceptions) for this specific material. Look up each code in 49 CFR 172.102 for the full text.

Need the full interactive record? Open UN 2949 in the SpillNerd lookup tool for the live database entry with placard graphics, GHS pictograms, full segregation tables, and synonym search. For another material, use the UN number and chemical lookup.

Reference data compiled from the DOT Hazardous Materials Table (49 CFR 172.101), the 2024 Emergency Response Guidebook, and public chemical databases (PubChem, NIOSH, EPA). Always verify the correct shipping description against the current regulation and the manufacturer's SDS Section 14 before shipping.