UN/NA Number Reference
DOT Class 8 Corrosive placard

UN 2331: Zinc chloride, anhydrous

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 2331 is assigned the proper shipping name Zinc chloride, anhydrous in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 8 Corrosive material, Packing Group III. 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 154)

Hazards: TOXIC. Corrosive. Non-combustible but may decompose producing toxic fumes when heated.

Fire: Use agent appropriate for surrounding fire. Cool containers.

Spill: Do not touch. Avoid inhalation. Use water spray to reduce fumes.

Chemical and Physical Properties

Zinc chloride is a white crystalline solid. It is soluble in water. It is corrosive to metals and therefore irritating to the skin, eyes and mucous membranes. It is used for preserving wood, in soldering fluxes, as a catalyst in chemical metals and manufacturing, and for many other uses.

CAS Number: 7646-85-7
Molecular Formula: Cl2Zn
Molecular Weight: 136.3 g/mol
Color / Form: White, very deliquesce granules, or fused pieces or rods
Odor: Odorless
Boiling Point: 1350 F
Melting Point: 554 °F (NIOSH, 2024)
Autoignition: Not flammable (USCG, 1999)
Specific Gravity: 2.91 (sinks in water)
Vapor Pressure: 0 mmHg (approx)
Water Solubility: 435 % at 70 F
pH: Aqueous solutions of zinc chloride are acidic (pH = 1.0 for 6 M)

Regulatory Data

CERCLA RQ (40 CFR 302.4)
1000 lb
OSHA PEL
1 1 mg/m 3 (ST) 2 mg/m 3
NIOSH REL
TWA 1 mg/m 3 ST 2 mg/m 3
IDLH
50 mg/m 3

A release of this material at or above its CERCLA reportable quantity (1000 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: IB8, IP3, T1, TP33. 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 2331 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.