Potassium chloride

Potassium chloride, also known as KCl or potassium salt, is a chemical made from potassium and chlorine. It looks like a white or clear crystal and has no smell. You can dissolve it in water, and it tastes like salt.

People use potassium chloride in many ways. It can replace regular table salt for people who need to watch their sodium. It is also used in farming to help plants grow, in medicines, and in home water softeners. You might also find it in food, where it is listed as additive E508.

Potassium chloride is found naturally in a mineral called sylvite. It is also found together with sodium chloride in a mineral called sylvinite.

Uses

Fertilizer

Most potassium chloride is used to make fertilizer, also called potash. Plants need potassium to grow well. Potassium chloride used on farms is called muriate of potash. It has a lot of potassium and is cheaper than other potassium sources. Potassium helps plants make food, use water, and stay healthy.

Medical use

Our bodies need potassium to work properly. Potassium chloride taken by mouth can help treat low levels of potassium in the blood. It is also used in special drinks for people who have lost fluids from sickness. Too much potassium chloride can be harmful.

Culinary use

Potassium chloride can be used instead of regular table salt in food. Some people find it tastes bitter, so it is often mixed with regular salt to make it taste better. Health guidelines suggest using lower-sodium salt substitutes for adults, but these are not recommended for children or some health conditions.

Industrial

In the past, about 5% of potassium chloride was used to make other chemicals, such as potassium hydroxide and chlorine.

Niche and archaic

Potassium chloride has a few special uses. It can be added to animal food to give animals more potassium. It is sometimes used in oil and gas work, and in water softeners at home. It can also be used to check radiation measuring tools and in some fire extinguishers. It was once used in old television screens and for welding aluminium, but these uses are rare today.

Toxicity

Potassium chloride is safe when eaten in small amounts, like what is normally in food. But if someone eats a lot of it, it can be harmful.

Chemical properties

KCl can dissolve in many polar liquids.

Mixes of KCl are often used to check the electrical conductivity of ionic liquids because KCl mixes stay the same, helping scientists make exact measurements. When mixed with water, KCl separates completely into K⁺ and Cl⁻ bits.

Potassium is more willing to give away electrons than sodium, but KCl can be turned into potassium metal by mixing it with sodium metal at very high heat, around 850 °C. The potassium, which turns into gas more easily, can be taken away by heating, following Le Chatelier's principle:

KCl_(l) + Na_(l) ⇌ NaCl_(l) + K_(g)

Scientists think that other mixes of potassium chloride might become stable under very high pressure, over 20 GPa. They have made and studied two types of KCl₃. Between 20-40 GPa, it forms a special shape with K⁺ and Cl₃⁻ bits; above 40 GPa, it changes into a shape like the metal mix Cr₃Si.

Physical properties

Potassium chloride looks like tiny crystals, similar to table salt. It can break apart easily in certain ways. When heated under pressure, its shape can change.

Some important traits include how it lets light pass through, how it bends light, and how well it carries heat. If you sprinkle powdered potassium chloride into a flame, it will show a beautiful lilac color.

Production

Potassium chloride comes from minerals such as sylvite, carnallite, and potash. It can also be taken from salt water or made through special processes like flotation or electrostatic separation. Some potassium chloride is made when nitric acid is produced from potassium nitrate and hydrochloric acid.

Most potassium chloride is made for farms and industries in places like Saskatchewan, Canada, Russia, and Belarus.

Laboratory methods

Potassium chloride is easy to buy, so it is not usually made in a lab. But it can be created by mixing potassium hydroxide with hydrochloric acid:

KOH + HCl → KCl + H₂O

This is a type of acid-base neutralization reaction. Another way is to let potassium burn with chlorine gas.