What is Potassium Chloride?

Potassium chloride is a naturally occurring compound made up of potassium and chlorine, and has the chemical formula KCl. This compound is used heavily in agriculture, is a component of some medications, and has a number of household uses. KCl has many of the same properties as regular table salt (NaCl): both are crystalline in form, dissolve easily, and can be absorbed by humans and plants. The two compounds are also halide salts, which refers to the presence of the element chlorine and gives them certain electrochemical properties. In chemical makeup and uses, however, the two salts are quite different.

The most common place to find potassium chloride is on a plant fertilizer ingredient list. This mineral is essential to organic growth, and both humans and plants depend on it for survival. While humans typically get all they need through food, plants, depending on the quality of the soil they are planted in, may not. Farmers often choose fertilizers enriched with potassium compounds in order to boost crop growth.

Potassium in chloride form is often the best vehicle to deliver this needed mineral. It is inexpensive, for one thing, and is also very easily absorbed by soil and plant roots. Other potassium compounds often take longer to break down, which can delay their effects.

Soil that is rich in potassium often yields fuller, richer crops. Plants exposed to the mineral grow bigger, brighter leaves and often produce more fruit. The science of adding this mineral is an exact one, though, and too much can be damaging to plants. Most commercial fertilizers have been analyzed and balanced by professionals to ensure that they contain only precise amounts of potassium and other minerals.

While most people get all the potassium they need through the foods they eat — fruits, vegetables, and meats are all good sources — not everyone does. People who suffer from deficiency, which is known as hypokalemia, may need to supplement their intake in pill form. The chloride compound is usually a better choice than straight potassium or other compounds in medication because of how easily and quickly it can be absorbed. Drugs and supplements containing this mineral are sold under many trade names, but usually list potassium chloride with the other active ingredients.

Hypokalemia is a serious condition. Not only is potassium essential to regular growth and functioning, it also plays a crucial role in keeping the heart beating. People with deficiencies often have weak or irregular heartbeats, which can be life threatening. They may also be chronically dehydrated. Slowly reintroducing the potassium chloride into the body helps boost electrolyte levels, which can prevent and treat dehydration caused by illness, excessive exercise, or intoxication.

Potassium chloride is often included in salt substitutes because of how much it resembles salt. The two substances taste similar, but potassium chloride crystals are often a bit bitter, and may do less to heighten or enhance the flavor of foods the way salt does. For this reason, it's usually only one of several ingredients in substitute products.

Most people don't need to take supplements that include this compound unless directed by a health care professional. People with hypokalemia almost always know that they are sick, and the risk of potassium deficiency among healthy people is relatively small. While getting a bit extra is rarely dangerous, people with certain medical conditions can be harmed by excessive quantities of this mineral.

Kidney disease sufferers in particular are usually advised to avoid supplemental potassium. When the kidneys are weak, they cannot process minerals as efficiently as they should, which can cause them to build up in the blood. The condition is known as hyperkalemia and is often just as serious as a deficiency.

It is not usually possible to overdose on naturally occurring potassium, as it exists in only small concentrations in most foods. In pill form, however, overdose can be a serious concern. While not getting enough potassium can slow a person's heartbeat, too much often stops it outright.

Potassium chloride is one of several drugs used in lethal injections — including executions and euthanasia. When injected it helps cause the heart to stop beating (cardiac arrest). Concentrated injections of the compound are almost always deadly. Taking too many potassium pills can also lead to death, but most of the time, a person will get very sick first, often experiencing irregular heart rhythms.

Many home improvement and pool supply stores sell loose potassium chloride salts for use in water softening systems. The idea of soft or hard water can sometimes be confusing, as it relates to mineral content rather than actual texture. Hard water is water that has a high mineral content. The precise makeup of hard water can vary, but calcium carbonate and magnesium are almost always present. Lime scale or calcium buildup in appliances is often caused by hard water.

When hard water is filtered through a trap containing potassium in chloride form, the chlorine ions bond to the minerals in the water and a chemical reaction happens. As a result, potassium ions enter the water, and corrosive elements like calcium chloride and magnesium remain trapped in the filter. Only very low concentrations of potassium are added to the filtered water.

When combined with other positive ions, particularly lithium, zinc, and ammonia, potassium chloride can be very helpful in calibrating molecule scales and other precise scientific equipment. It is especially useful in radiation monitoring equipment. When exposed to high temperatures, potassium produces beta radiation and serves as an optical crystal, or prism, that can help scientists assess transmission precision.

Common batteries may also contain potassium chloride. The compound serves as a bridge between copper sulfate and zinc sulfate, which enables the flow of electrons between the electrodes.

In some places, the chloride compound may also be used as an "environmentally friendly" way of melting ice. It is usually as effective as salt, but does not leave behind any residue. Excess potassium is usually absorbed by nearby plants once the ice melts.

Early fire extinguishers contained potassium chloride, as the compound can be effective at smothering flames. Advances in the fire fighting field have turned up a number of more efficient compounds for this purpose, however. Still, in major disasters such as wildfires, the chloride compound may still be used — but usually in later phases, as the blazes begin to subside.