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Chloride

physical science Maturity 7-9 Next article →

Chloride is a chemical term that describes many different types of molecules or compounds. It can refer to a chloride anion, which is a negatively charged chlorine atom. It can also describe a neutral chlorine atom that is covalently bonded to other atoms by a single bond.

Chloride-ion-3D-vdW
Chloride-ion-3D-vdW

This substance is vital to both the physical world and living organisms. It acts as an essential electrolyte in all body fluids. It is responsible for maintaining acid-base balance and regulating liquid flow in and out of cells. Without chloride, the delicate systems inside our bodies would not function correctly.

To understand chloride, we must look at its electronic properties. A chloride ion has a diameter of 181 pm, which is much larger than a standard chlorine atom at 99 pm. This size difference happens because the anion has one extra electron. This extra electron makes the atom's hold on its valence shell weaker.

NaCl polyhedra
NaCl polyhedra

In water, chloride is usually highly soluble, meaning it dissolves easily. However, some specific salts like silver chloride or mercury(I) chloride are only slightly soluble. When dissolved in water, chloride is bonded by the protic end of the water molecules.

Chloride can exist in several different chemical states through a process called oxidation. Chlorine can assume several oxidation states, including -1, +1, +3, +5, and +7. At a -1 state, it is called chloride. At a +1 state, it is hypochlorite, which is the active ingredient in bleach.

Hypochlorite-3D-vdW
Hypochlorite-3D-vdW

Other states include chlorite (+3), chlorate (+5), and perchlorate (+7).

Hypochlorite-3D-vdW
Hypochlorite-3D-vdW

These different forms allow chlorine to participate in many different chemical reactions. For example, chloride can be oxidized into chlorine gas during the chlor-alkali process.

In the natural world, chloride is most commonly found in seawater. The concentration of chloride ions in seawater is approximately 19,400 mg per liter.

You can also find it in higher concentrations in inland seas or subterranean brine wells. Examples include the Great Salt Lake in Utah and the Dead Sea in Israel. Because most chloride salts dissolve in water, chloride-containing minerals are usually found in dry climates or deep underground. Common minerals include halite, which is sodium chloride, and sylvite, which is potassium chloride.

Biology relies heavily on chloride to maintain homeostasis. It is the most abundant extracellular anion in the body. It accounts for about one third of the tonicity in extracellular fluid. In mammalian cells, chloride concentrations typically range from 5 to 100 mM. In blood plasma, the concentration is around 100 mM.

Chloride-ion-3D-vdW
Chloride-ion-3D-vdW

Chloride also helps transmit action potentials in neurons through chloride channels. Additionally, the stomach requires chloride to produce hydrochloric acid for digestion.

The kidneys are the primary organs responsible for regulating serum chloride levels. Most chloride is filtered through a structure called the glomerulus. From there, the kidneys reabsorb most of it through the proximal and distal tubules. This happens through both active and passive transport. This regulation is crucial because high concentrations of chloride can have ecological effects. It can contribute to the acidification of streams or affect how aquatic plants and animals reproduce.

Human industry uses chloride in many massive and useful ways. The chlor-alkali industry is a major consumer of the world's energy. This process uses electrolysis to convert sodium chloride solutions into chlorine and sodium hydroxide.

Chloralkali membrane
Chloralkali membrane

We also use calcium chloride as a de-icer to lower the melting point of ice on roads. In the petroleum industry, engineers monitor chloride levels in drilling mud. An increase in chloride can signal that they have hit a high-pressure saltwater formation. From the salt on our food to the regulation of our blood, chloride is a fundamental part of our existence.

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🖼️ Images & Media (7)
File:Chloride-ion-3D-vdW.png
Chloride-ion-3D-vdW.png
File:Hypochlorite-3D-vdW.png
Hypochlorite-3D-vdW.png
File:Chlorite-3D-vdW.png
Chlorite-3D-vdW.png
File:Chlorate-3D-vdW.png
Chlorate-3D-vdW.png
File:Perchlorate-3D-vdW.png
Perchlorate-3D-vdW.png
File:NaCl polyhedra.png
NaCl polyhedra.png
File:Chloralkali membrane.svg
Chloralkali membrane.svg
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