Clorul

Clorul, or chlorine, is a chemical element with the symbol Cl and atomic number 17. It is the lightest halogen and a nonmetal. In Romanian usage, "clorul" refers to this element. Chlorine is highly reactive and does not occur freely in nature; it is mainly found as chloride salts in minerals and in seawater.

Chlorine is produced industrially by the electrolysis of sodium chloride solutions in the chlor-alkali process, yielding chlorine gas, sodium hydroxide, and hydrogen. It can also be generated as a by-product in some metallurgical processes.

Physically, chlorine at room temperature is a yellow-green gas with a strong, pungent odor. It is denser than air and highly reactive, acting as a powerful oxidizing agent. When dissolved in water, it forms hydrochloric acid and hypochlorous acid, contributing to its disinfection properties.

Applications include water treatment and sanitation (drinking water disinfection, pool sanitization), paper and textile bleaching, and the production of a wide range of chemicals, notably polyvinyl chloride (PVC) and various organochlorine compounds.

Safety and environmental aspects: chlorine gas is toxic, corrosive, and can cause respiratory and eye irritation on exposure. It reacts vigorously with hydrogen to form hydrogen chloride. Large releases require prompt emergency response. Environmental concerns include the use of organochlorine compounds and the potential role of chlorine chemistry in ozone depletion.

History: chlorine was first isolated by Carl Wilhelm Scheele in 1774 and later recognized as an element by Humphry Davy. The name chlorine derives from the Greek chloros, meaning greenish-yellow, reflecting the color of the gas.