Carbon and its Compounds

Potassium Chloride

Potassium chloride also called Sylvite, KCl, or potassium salt is a metal halide salt. It is composed of potassium and chlorine. It is an ionic salt with a bond between an alkali metal and a halogen. Potassium Chloride is made up of potassium cations and chloride anions in a 1:1 ratio. Potassium chloride is known for its colourless, crystalline appearance and odourless smell. Though in its solid form, potassium chloride easily dissolves in water, and the resulting solution of KCl is said to have a salty taste.

The main application of this ionic salt is in the agriculture industry, where it is in use in the production of crop fertilizers. Potash i.e., a water-soluble crystalline material that is in use for fertilization. It can also be prepared from potassium chloride and other minerals. This compound is also in use as a substitute for common salt that is sodium chloride in food. Oral consumption of appropriate quantities of KCl helps treat low blood potassium in the human body.

Potassium Chloride

Production of Potassium Chloride

Potassium chloride is drawn out from minerals sylvite, carnallite, and potash. It is also drawn out from salt water and can be produced by crystallization from solution, flotation, or electrostatic separation from suitable minerals. Potassium chloride is a by-product of the production of nitric acid from potassium nitrate and hydrochloric acid.

The vast majority of potassium chloride is manufactured as agricultural and industrial grade potash in  Saskatchewan, Canada, Russia and Belarus.

Laboratory Methods

Potassium chloride is easily available and is rarely prepared in the laboratory. It can be produced by treating  potassium hydroxide with hydrochloric acid:

\(KOH + HCl \rightarrow  KCl + H_2O\)

This conversion is an acid-base neutralization reaction. The resulting salt can is purified by recrystallization. Another way is to allow potassium to burn in the presence of chlorine gas, it is an exothermic reaction:

\(2 K + Cl_2 \rightarrow 2 KCl\)

Properties of Potassium Chloride

KCl in its solid-state gets readily soluble in many polar solvents, including water. The salt is ionized into the \(K^+\) cation and the \(Cl^- \) anions. Other physical and chemical properties of potassium chloride are as follows:

Physical Properties

  • The crystals of potassium chloride have a face-centred cubic (FCC) lattice.
  • The molar mass of potassium chloride is 74.5513 grams/mol.
  • Also, the density potassium chloride in the solid, crystalline form is 1.984 grams per cubic centimetre.
  • The melting and boiling points of potassium chloride are 1040 K and 1690 K respectively.
  • At \(0^oC\), \(20^oC\), and \(100^oC\), the solubility of potassium chloride in water corresponds to 217.1 g/L, 253.9 g/L, and 360.5 g/L respectively.
  • Potassium chloride is highly soluble in alcohols.

Chemical Properties

  • Potassium chloride is completely ionized into \(K^+\) and \(Cl^+\) ions in water. The resulting aqueous solution has high values of electrical conductivity.
  • The reduction of potassium chloride into metallic is done with the help of metallic sodium, despite the lower electropositivity of sodium if compared to potassium.

Uses of Potassium Chloride

Some important uses of potassium chloride are-

  • Potassium chloride is in use to manufacture potash. It is an important form of fertilizer that enriches soils with potassium. It promotes the growth of plant life. The potash fertilizers made from potassium chloride make up the majority of potash fertilizers sold worldwide.
  • The treatment of low blood pressure employs potassium chloride as a part of the medication.
  • Potassium chloride is in use as a salt substitute in food.
  • Potassium chloride is an important raw material required in the manufacture of potassium metal.
  • The metal halide salt KCl is in use in the manufacture of soaps. Water softening units involve the use of KCl as an alternative to sodium chloride as well.
  • The use of potassium chloride as a source of beta radiation is useful in calibrating radiation monitoring equipment.

FAQs on Potassium Chloride

Question 1: Is potassium chloride the same as salt?

Answer: The food industry uses the mineral salt compound as an alternative to standard table salt i.e., sodium chloride. Experts note that potassium chloride gives flavour without increasing their regular intake of sodium. The FDA policy requires the product to be branded as “potassium chloride salt” by makers.

Question 2: What are the side effects of potassium chloride?

Answer: It can cause stomach pain, nausea, vomiting, discomfort, or diarrhoea. When any of those symptoms continue or worsen, one must immediately inform your doctor or pharmacist. When you have some severe side effects, including difficult or painful swallowing, concern the doctor straight away.

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