What is Chlorine? - Facts, Uses, Properties & Formula

Instructor: Laura Foist

Laura has a Masters of Science in Food Science and Human Nutrition and has taught college Science.

In this lesson we will learn about chlorine - its history, function as a disinfectant, oxidizer, place in the periodic table and what it means for it to be a halogen.

What is Chlorine?

That smell of swimming on a hot summer day. The sun screen, the plastic floating tubes, and of course the chlorinated pool. That smell is very distinctive to almost everyone. For some that is the smell of summer. It is what they look forward to all year long. For others it is the smell of bad water and it is why they will only drink bottled, non-chlorinated water. Whatever your thoughts when you think of chlorine, it is obvious that chlorine is very prominent in our lives. Its main function is as a disinfectant in many different industries.

Chlorine was first produced, in the pure form, in 1774 by Carl Wilhelm. He realized that this greenish colored gas would bleach paper and discolor flowers and leaves. He also noted the choking smell of the chlorine gas. Then in 1807, Humphry Davy discovered that this chlorine gas is a simple element, instead of a combination of elements, and it was added to the list of known elements in 1820.

Functions of Chlorine

Chlorine is most commonly known for its use in water, since it is a great disinfectant and kills bacteria. When put into the water source it will remain there, (in low doses), until it reaches the consumer. This allows the disinfectant action of chlorine to continue even after the water leaves the water purifier. Chlorine can also be used as a disinfectant to clean areas such as hospitals and food processing plants. It is also used in dyes, bleaching, making plastic, as an oxidizing agent, and in the past for chemical war-fare.

Chlorine is also commonly used as a dye to bleach products such as clothes or bleached white flour. This gives a white color to products. It is also the cause of hair changing color if someone goes swimming too frequently. The element chlorine is able to react with compounds in flour, or your hair, and causes the color to change.

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