Potassium chloride is a salt formed from the bonding between an alkali metal and a halide. It consists of a Potassium atom bonding with a Chloride atom. The Potassium chloride chemical formula is KCl. It is formed when the one excess electron in the valence shell of the Potassium atom is transferred to the valence shell of the Chlorine atom so that both the atoms complete their octet valency.
Structure of Potassium Chloride
Potassium chloride is formed due to the formation of the ionic bonds between the potassium and chlorine atom. Since the electron is transferred between the two atoms, the bond formation is ionic in nature. The atoms are closely packed, where the larger chloride ions are distributed in an array with gaps, also known as octahedral voids, between them. The smaller potassium ions fill in these gaps. Such chemical structure is also observed in the crystal structure of other halide salts.
Properties of potassium chloride
The identity of any chemical compound is defined by its physical and chemical properties. The physical and chemical properties of Potassium chloride are as follows:
Physical properties
It is an odorless, crystalline, white solid with a sour taste.
Face-centered cubic unit cells form the crystal structure of Potassium chloride.
The melting point of Potassium chloride is 770ᴼC.
The boiling point of Potassium chloride is 1420ᴼC.
The density of Potassium chloride is 1.984 g/mL.
The molar mass of Potassium chloride is 74.5513 g/ mol.
Potassium chloride is soluble in water, alcohol, but not in ether. It is also not soluble in organic compounds with the general formula of R-O-R’.
The solubility of Potassium chloride in water increases with temperature. It is due to the increased Brownian motion caused between the atoms in increased temperature. The solubility of Potassium chloride is 217.1 g/L at 0ᴼC, 253.9 g/L at 20ᴼC, and 360.5 g/L at 100ᴼC.
The pH of Potassium chloride is about 7.
Chemical Properties
Potassium chloride can be completely ionized into potassium and chloride ion in water. Therefore, an aqueous solution of Potassium chloride gas very high electrical conductivity.
Potassium chloride can be reduced to potassium by reacting with sodium, although the position of sodium in the electropositivity series is lower than that of potassium. The dissociation reaction of Potassium chloride into potassium by sodium takes place at 850ᴼC.
kcl in Chemistry - KCl+Na⇌ NaCl + K –
Potassium Chloride burns with lilac or a pale violet-colored flame, and this is the characteristic for most potassium-containing compounds.
KCl is widely used in chemistry as an essential component of most chemical reactions.
Uses of potassium chloride
The application of potassium chloride has extended into industrial and medical arenas. Some of the uses of potassium chloride are as under:
It is used widely as a component for agricultural fertilizer. It is used to make Potash, which is an important source of potassium for plant growth.
It is used to treat cases of extremely low blood pressure.
It is used in cooking as a substituent for sodium chloride since it is required in a lesser amount.
It is used for cooking food for high blood pressure patients.
It is used in the industry as the raw material to manufacture potassium metal.
It is used in the soap industry as a water softening agent as an alternative to sodium chloride.
Potassium chloride can be used in the calibration of radiation monitoring equipments as a source for beta radiation.
Potassium chloride is used for the flux in oxy-fuel welding machines for the welding of aluminum. This is one of the important KCL uses.
FAQs on Potassium Chloride
1. What exactly is Potassium Chloride and what is its chemical formula?
Potassium Chloride is an ionic salt composed of potassium and chlorine. Its chemical formula is KCl. It consists of potassium cations (K⁺) and chloride anions (Cl⁻) held together by strong ionic bonds in a 1:1 ratio. It appears as a white, crystalline solid and is odourless.
2. Is Potassium Chloride the same as the common table salt used in cooking?
No, they are different compounds. Common table salt is Sodium Chloride (NaCl), while Potassium Chloride is KCl. Although both are metal halides with similar crystalline structures, their primary cations differ. KCl is sometimes used as a salt substitute for people on low-sodium diets, but it has a slightly bitter or metallic taste compared to NaCl.
3. What are the most important uses of Potassium Chloride in various industries?
Potassium Chloride has several significant applications, including:
- Agriculture: Its primary use is as a fertilizer, often called muriate of potash (MOP), to provide essential potassium for plant growth.
- Medicine: It is used to treat and prevent low potassium levels in the body (hypokalemia).
- Food Industry: It serves as a salt substitute in low-sodium foods and as a firming agent or flavour enhancer.
- Industrial Applications: It is used in water softening, as a de-icing agent, and as a raw material for manufacturing other potassium compounds like potassium hydroxide.
4. How does Potassium Chloride help in plant growth when used as a fertilizer?
As a fertilizer, Potassium Chloride (muriate of potash) is a vital source of potassium (K), which is one of the three primary macronutrients plants need. Potassium plays a crucial role in regulating a plant's water balance (stomata control), activating enzymes, and improving overall plant vigour, disease resistance, and crop yield quality.
5. What is the fundamental difference between Potassium Chloride (KCl) and Potassium Chlorate (KClO₃)?
The key difference lies in their chemical composition and properties. Potassium Chloride (KCl) is a simple salt where chlorine has an oxidation state of -1. It is stable and used in fertilizers and medicine. In contrast, Potassium Chlorate (KClO₃) contains the chlorate ion (ClO₃⁻), where chlorine has an oxidation state of +5. This makes KClO₃ a powerful oxidizing agent, commonly used in fireworks, explosives, and as a disinfectant.
6. Why can molten or aqueous Potassium Chloride conduct electricity, but solid KCl cannot?
This phenomenon is due to the mobility of ions. In its solid state, the K⁺ and Cl⁻ ions in Potassium Chloride are held in fixed positions within a rigid crystal lattice and are unable to move. When KCl is molten or dissolved in water, these ions become free to move. These mobile, charged particles can then travel towards oppositely charged electrodes, carrying an electric current.
7. How is the crystal lattice of Potassium Chloride structured according to the CBSE syllabus?
As per the concepts in the Class 12 Chemistry syllabus, Potassium Chloride has a face-centred cubic (FCC) crystal structure, similar to Sodium Chloride. This structure can be visualized as two interpenetrating FCC lattices, one of potassium ions (K⁺) and one of chloride ions (Cl⁻), where each ion is surrounded by six ions of the opposite charge in an octahedral arrangement.
8. How is Potassium Chloride commercially prepared from its natural ores?
Potassium Chloride is primarily extracted from ores like sylvinite (a mixture of KCl and NaCl) and carnallite (KCl·MgCl₂·6H₂O). The most common method is fractional crystallization. This process exploits the different solubilities of KCl and NaCl at varying temperatures. The ore is dissolved in hot brine, and as the solution cools, KCl, being less soluble at lower temperatures, crystallizes out first, allowing it to be separated from other salts.
