Potassium chloride

The sodium chloride as sylvinite.

Chemical properties

Potassium chloride can react as a source of metal ion:

KCl(aq) + KNO₃(aq)

Although potassium is more electropositive than Le Chatelier's principle):

KCl(l) + Na(l) ⇌ NaCl(l) + K(g)

This method is the main method for producing metallic sodium) fails because of the high solubility of potassium in molten KCl.

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

Manufacture/Extraction

Potassium chloride occurs naturally as hydrochloric acid.

Uses

The majority of the potassium chloride produced is used for making gamma with 1.46083 MeV. Potassium chloride makes up 70% of Ace Hardware's allegedly pet and vegetarian friendly "Ice Melt" though inferior in melting quality to calcium chloride (0° F v. -25° F).

Biological and medical properties

Potassium is vital in the human body and oral potassium chloride is the common means to replenish it, although it can also be diluted and given hyperkalemia which can lead to paresthesia, cardiac conduction blocks, fibrillation, arrhythmias, and sclerosis.

Dr. Jack Kevorkian's thanatron machine injected a lethal dose of potassium chloride into the patient, which caused the heart to stop functioning, after a sodium thiopental-induced coma was achieved.

Physical properties

Potassium chloride has a crystalline structure like many other salts. Structure: face-centered cubic. Lattice Constant: roughly 6.3 angstroms.

In chemistry and physics it is a very commonly used as a standard, for example as a calibration standard solution in measuring electrical conductivity of (ionic) solutions, since carefully prepared KCl solutions have well-reproducible and well-repeatable measurable properties.

Precautions

Orally it is toxic in excess; the LD₅₀ is around 2500 mg/kg (meaning that a person weighing 75 kg (165 lb) would have to consume about 190 g (6.7 oz); regular salt is about as toxic). Intravenously this is reduced to just over 100 mg/kg but of more concern are its severe effects on cardiac muscles; high doses can cause cardiac arrest and rapid death. A massive overdose of intravenous potassium chloride is used to stop the heart in execution by lethal injection.

References

1. ^ Bernard Martel. Chemical Risk Analysis: A Practical Handbook. Kogan, 2004, page 369. ISBN 1903996651.

• Handbook of Chemistry and Physics, 71st edition, CRC Press, Ann Arbor, Michigan, 1990.
• N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, Pergamon Press, 1984. ISBN 0-08-022057-6