UN/NA Number Reference
DOT Class 6.1 Toxic Substance placard

UN 1643: Mercury potassium iodide

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1643 is assigned the proper shipping name Mercury potassium iodide in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 6.1 Toxic Substance material, Packing Group II. Required label(s): 6.1.

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 151)

Hazards: TOXIC. May be fatal if inhaled, ingested, or absorbed through skin. Contact may cause burns.

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

Spill: Do not touch. Avoid inhalation. Use water spray to reduce dust/vapor. Ventilate.

Chemical and Physical Properties

Mercuric potassium iodide, [solid] appears as odorless yellow crystals. Crystallizes with either one, two or three molecules of water. Soluble in water and denser than water. Commercially available in the anhydrous form. Highly toxic by ingestion, inhalation, and skin absorption.

CAS Number: 7783-33-7
Molecular Formula: HgI4K2
Molecular Weight: 786.41 g/mol
Color / Form: Yellow crystals
Odor: Odorless
Specific Gravity: 4.29 (sinks in water)
Water Solubility: Very sol in water
pH: Neutral or alkaline to litmus

Special Provisions

49 CFR 172.102 special provision codes for this entry: IB8, IP2, IP4, T3, 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 1643 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.