Potassium chloride

Potassium chloride

Names
Other names Sylvite Muriate of potash
Identifiers
CAS Number	7447-40-7 Y
3D model ( JSmol )	Interactive image
ChEBI	CHEBI:32588 Y
ChEMBL	ChEMBL1200731 N
ChemSpider	4707 Y
DrugBank	DB00761 Y
ECHA InfoCard	100.028.374
E number	E508 (acidity regulators, ...)
KEGG	D02060 Y
PubChem CID	4873
RTECS number	TS8050000
UNII	660YQ98I10 Y
CompTox Dashboard (EPA)	DTXSID5021178
InChI InChI=1S/ClH.K/h1H;/q;+1/p-1 Y Key: WCUXLLCKKVVCTQ-UHFFFAOYSA-M Y InChI=1/ClH.K/h1H;/q;+1/p-1 Key: WCUXLLCKKVVCTQ-REWHXWOFAZ
SMILES [Cl-].[K+]
Properties
Chemical formula	KCl
Molar mass	74.555 g·mol−1
Appearance	white crystalline solid
Odor	odorless
Density	1.984 g/cm3
Melting point	770 °C (1,420 °F; 1,040 K)
Boiling point	1,420 °C (2,590 °F; 1,690 K)
Solubility in water	27.77 g/100mL (0 °C) 33.97 g/100mL (20 °C) 54.02 g/100mL (100 °C)
Solubility	Soluble in glycerol, alkalies Slightly soluble in alcohol Insoluble in ether[1]
Solubility in ethanol	0.288 g/L (25 °C)[2]
Acidity (pKa)	~7
Magnetic susceptibility (χ)	−39.0·10−6 cm3/mol
Refractive index (nD)	1.4902 (589 nm)
Structure
Crystal structure	face centered cubic
Space group	Fm3m, No. 225
Lattice constant	a = 629.2 pm[3]
Coordination geometry	Octahedral (K+) Octahedral (Cl−)
Thermochemistry
Std molar entropy (S⦵298)	83 J·mol−1·K−1[4]
Std enthalpy of formation (ΔfH⦵298)	−436 kJ·mol−1[4]
Pharmacology
ATC code	A12BA01 (WHO) B05XA01 (WHO)
Routes of administration	Oral, IV, IM
Pharmacokinetics:
Excretion	Kidney: 90%; Fecal: 10%[5]
Hazards
NFPA 704 (fire diamond)	1 0 0
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (median dose)	2600 mg/kg (oral, rat)[6]
Safety data sheet (SDS)	ICSC 1450
Related compounds
Other anions	Potassium fluoride Potassium bromide Potassium iodide
Other cations	Lithium chloride Sodium chloride Rubidium chloride Caesium chloride Ammonium chloride
Related compounds	Potassium hypochlorite Potassium chlorite Potassium chlorate Potassium perchlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Potassium chloride (KCl, or potassium salt) is a

It occurs naturally as the mineral sylvite, which is named after salt's historical designations sal degistivum Sylvii and sal febrifugum Sylvii,^[9] and in combination with sodium chloride as sylvinite.^[10]

Uses

Fertilizer

The majority of the potassium chloride produced is used for making fertilizer, called potash, since the growth of many plants is limited by potassium availability. Potassium chloride sold as fertilizer is known as muriate of potash. The vast majority of potash fertilizer worldwide is sold as muriate of potash.^{[citation needed]}

Medical use

Potassium is vital in the

In the United States, potassium chloride is used as the final drug in the three injection sequence of lethal injection as a form of capital punishment. It induces cardiac arrest, ultimately killing the inmate.^[14]

Industrial

This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources in this section. Unsourced material may be challenged and removed. (September 2022) (Learn how and when to remove this template message)

As a chemical

Glass manufacturers use granular potash as a flux, lowering the temperature at which a mixture melts. Because potash imparts excellent clarity to glass, it is commonly used in eyeglasses, glassware, televisions, and computer monitors.

Because natural potassium contains a tiny amount of the isotope

Potassium chloride is used in some

The typical amounts of potassium chloride found in the diet appear to be generally safe.[15] In larger quantities, however, potassium chloride is toxic. The LD₅₀ of orally ingested potassium chloride is approximately 2.5 g/kg, or 190 grams (6.7 oz) for a body mass of 75 kilograms (165 lb). In comparison, the LD₅₀ of sodium chloride (table salt) is 3.75 g/kg.

Intravenously, the LD₅₀ of potassium chloride is far smaller, at about 57.2 mg/kg to 66.7 mg/kg; this is found by dividing the lethal concentration of positive potassium ions (about 30 to 35 mg/kg)^[16] by the proportion by mass of potassium ions in potassium chloride (about 0.52445 mg K⁺/mg KCl).^[17]

Chemical properties

Solubility

KCl is soluble in a variety of polar solvents.

Solutions of KCl are common standards, for example for

This method is the main method for producing metallic potassium. Electrolysis (used for sodium) fails because of the high solubility of potassium in molten KCl.^[10]

Other potassium chloride stoichiometries

Potassium chlorides with formulas other than KCl have been predicted to become stable under pressures of 20 GPa or more.^[19] Among these, two phases of KCl₃ were synthesized and characterized. At 20-40 GPa, a trigonal structure containing K⁺ and Cl₃⁻ is obtained; above 40 GPa this gives way to a phase isostructural with the intermetallic compound Cr₃Si.

Physical properties

Under ambient conditions the crystal structure of potassium chloride is like that of NaCl. It adopts a face-centered cubic structure known as the B1 phase with a lattice constant of roughly 6.3 Å. Crystals cleave easily in three directions. Other polymorphic and hydrated phases are adopted at high pressures.^[20]

Some other properties are

• Transmission range: 210 nm to 20 µm
• Transmittivity = 92% at 450 nm and rises linearly to 94% at 16 µm
• Refractive index = 1.456 at 10 µm
• Reflection loss = 6.8% at 10 µm (two surfaces)
• dN/dT (expansion coefficient)= −33.2×10⁻⁶/°C
• dL/dT (refractive index gradient)= 40×10⁻⁶/°C
• Thermal conductivity = 0.036 W/(cm·K)
• Damage threshold (Newman and Novak): 4 GW/cm² or 2 J/cm² (0.5 or 1 ns pulse rate); 4.2 J/cm² (1.7 ns pulse rate Kovalev and Faizullov)

As with other compounds containing potassium, KCl in powdered form gives a lilac flame.

Production

Potassium chloride is extracted from minerals

The vast majority of potassium chloride is produced as agricultural and industrial grade potash in Saskatchewan, Canada, as well as Russia and Belarus. Saskatchewan alone accounted for over 25% of the world's potash production in 2017.^[21]

Laboratory methods

Potassium chloride is inexpensively available and is rarely prepared intentionally in the laboratory. It can be generated by treating potassium hydroxide (or other potassium bases) with hydrochloric acid:

${\displaystyle {\ce {KOH + HCl -> KCl + H2O}}}$

This conversion is an acid-base neutralization reaction. The resulting salt can then be purified by recrystallization. Another method would be to allow potassium to burn in the presence of chlorine gas, also a very exothermic reaction:

${\displaystyle {\ce {2 K + Cl2 -> 2 KCl}}}$

References