Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the Pauling scale, behind only oxygen and fluorine. Chlorine played an important role in the experiments conducted by medieval alchemists, which commonly involved the heating of chloride salts like ammonium chloride (sal ammoniac) and sodium chloride (common salt), producing various chemical substances containing chlorine such as hydrogen chloride, mercury(II) chloride (corrosive sublimate), and hydrochloric acid (in the form of aqua regia). Wikipedia

Substance Data

Source: TOXNET



Flash Point


Boiling Point


Emergency Response Guide No. 124

Data from the Hazardous Materials Table

Source: 49 CFR §172 (2018/07)

(3) Hazard Class

Poisonous gas

(4) Identification number Help

UN 1017

(5) Packing Group Help


(6) Labels Help

Poisonous gas (2.3) Oxidizers (5.1) Corrosive liquids (8)

(7) Special Provisions (§172.102) Help

Special provisions may be very complex. The extracts are taken from 49 CFR §172.102. Please be careful with the information, as necessary, additional conditions may be applied that are not written here. Please check the original source and report bugs.

(8) Packing Authorizations (§173.***) Help

(8A) ExceptionsNone
(8B) Non-bulk304see 49 CFR §173.304
(8C) Bulk314, 315see 49 CFR §173.314, 315

(9) Quantity Limits Help

(9A) Passenger aircraft/railForbidden
(9B) Cargo aircraft onlyForbidden

(10) Vessel stowage Help

(10A) Location
(10B) Other

Segregation Chart for Load, Transport, Storage

In this table a statement is contained for each hazard class whether the loading, transport or storage with other hazard classes is allowed, is not permitted or is restricted. The table is based on U.S.-Code 49 CFR §177.848.

red May not be loaded, transported, or stored together in the same transport vehicle or storage facility.
green Load, transport, storage together is not restricted.
yellow Load, transport, storage together is allowed under restrictions.