Product Information

CAS Number:


Chemical and physical data

Formula : CL

Atomic Mass: 35.453 u

Density : 3.2 g/L

Melting point : −101.5 °C

Boiling point : −34.04 °C

 Other Names

Diatomic chlorine

Chlorine Gas


Liquified Chlorine gas


What is chlorine?

Chlorine’s disinfection properties have helped improve the lives of billions of people around the world. Chlorine also is an essential chemical building block, used to make many products that contribute to public health and safety, advanced technology, nutrition, security and transportation. Food, water and medicines, computers and cell phones all depend on chlorine chemistry. Chlorine chemistry also is used in the manufacture of numerous products ranging from solar panels, to bullet-resistant vests, paint.

History and Uses:

Since it combines directly with nearly every element, chlorine is never found free in nature. Chlorine was first produced by Carl Wilhelm Scheele, a Swedish chemist, when he combined the mineral pyrolusite (MnO2) with hydrochloric acid (HCl) in 1774. Today, most chlorine is produced through the electrolysis of aqueous sodium chloride (NaCl).

Chlorine is commonly used as an antiseptic and is used to make drinking water safe and to treat swimming pools. Large amounts of chlorine are used in many industrial processes, such as in the production of paper products, plastics, dyes, textiles, medicines, antiseptics, insecticides, solvents and paints.

Two of the most familiar chlorine compounds are sodium chloride (NaCl) and hydrogen chloride (HCl). Sodium chloride, commonly known as table salt, is used to season food and in some industrial processes. Hydrogen chloride, when mixed with water (H2O), forms hydrochloric acid, a strong and commercially important acid. Other chlorine compounds include: chloroform (CHCl3), carbon tetrachloride (CCl4), potassium chloride (KCl), lithium chloride (LiCl), magnesium chloride (MgCl2) and chlorine dioxide (ClO2).

Chlorine is a very dangerous material. Liquid chlorine burns the skin and gaseous chlorine irritates the mucus membranes. Concentrations of the gas as low as 3.5 parts per million can be detected by smell while concentrations of 1000 parts per million can be fatal after a few deep breaths.

Why Do Swimming Pools Need Chlorine?

Most of us are used to the idea that swimming pools need chlorine. We know that it keeps the pool clean, but we also know that there are downsides. It is common knowledge that too much chlorine can produce an unpleasant chemical odor, make your skin irritated, cause red eyes, and even dye your green. The fact is, chlorine is a widely misunderstood chemical. Its role in swimming pool sanitation is critical, and when used correctly it is actually completely safe.

Applications of chlorine


Chlorine chemistry helps keep drinking water and swimming pools safe. Before cities began routinely treating drinking water with chlorine-based disinfectants, thousands died every year from waterborne diseases such as cholera, typhoid fever, dysentery and hepatitis A. Chlorine-based pool and spa disinfectants help keep recreational waters safe by destroying waterborne pathogens that can result in illnesses, such as diarrhea, swimmer’s ear or skin rashes, including athlete’s foot.

Household Disinfectant

Chlorine chemistry is used to manufacture household chlorine bleach, which whitens and disinfects clothes and disinfects kitchen and bathroom surfaces. Diluted bleach and water solutions are especially effective at killing germs that may be found on household surfaces that make people sick, including the norovirus and seasonal flu.


Chlorine compounds are widely used in the food industry to kill bacteria and disinfect.
Examples include treating pasteurizer cooling water, washing fruit and vegetables and
disinfecting food contact surfaces.


Chlorine chemistry is critical to manufacturing medicines we depend on, including some that help lower cholesterol, control arthritis pain and relieve allergy symptoms. The products of chlorine chemistry can also be found in blood bags, medical devices and surgical stitches. Chlorine chemistry is also used to manufacture contact lenses, safety glasses and respiratory inhalers.

Energy and Environment

Chlorine chemistry plays an important role in harnessing solar energy, purifying the silicon in grains of sand and helping transform them into solar panel chips. Wind turbine blades made from chlorine-based epoxy resins help convert wind power into electricity.

Advanced Technology

Chlorine chemistry is used to manufacture fast processors that power smart phones, tablets, and computers. Chlorine chemistry is also used to manufacture residential and commercial air conditioning refrigerants, hybrid car batteries and high-performance magnets.

Defense and Law Enforcement

Chlorine chemistry is used to manufacture bullet-resistant vests worn by soldiers and police officers. Chlorine chemistry is also used to produce parachutes and night vision goggles as well as cockpit canopies and missile guidance technologies.


Chlorine chemistry is used on planes, trains, automobiles, and boats, in the manufacture of seat cushions, bumpers, brake fluid and airbags that help keep passengers safe and comfortable. Chlorine chemistry is also used to manufacture shatter-resistant windows, wire and cable, steel hulls, and navigation systems.


Chlorine is an important chemical element in water treatment, disinfectants in bleach, and sanitizer. Chlorine is also used in the manufacture of a wide range of everyday items.