Halogen observed to react with hydrogen to form hydrogen halides. For fluorine, chlorine, and bromine, this reaction is in the form of: However, hydrogen iodide and hydrogen astatide can split back into their constituent elements. The hydrogen-halogen reactions get gradually less reactive toward the heavier halogens. A fluorine-hydrogen reaction is explosive even when it is dark and cold. A chlorine-hydrogen reaction is also explosive, but only in the presence of light and heat. A bromine-hydrogen reaction is even less explosive; it is explosive only when exposed to flames. Iodine and astatine only partially react with hydrogen, forming equilibria. All halogens form
Bromine production in the United States rail access, and difficult highway access, and was shut down in 1945. Dow found a better permanent location at Freeport, Texas, where a seawater extraction plant started in 1940, and a second in 1943. The Freeport plants recovered magnesium, sodium compounds, and chlorine, in addition to the bromine. The Freeport chemical operations are still active, but they stopped extracting bromine in 1969. Brine mining Bromine production in the United States Bromine production in the United States of 225,000 tonnes in 2013 made that country the second-largest producer of bromine, after Israel. The US supplied 29 percent of world production. Since