Difference between revisions of "Potassium chloride"

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| Name = Potassium chloride
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| IUPACName = Potassium chloride
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| OtherNames = Muriate of potash<br>Sylvite
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| Appearance = White solid
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| BoilingPtC = 1420
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| Density = 1.984 g/cm<sup>3</sup>
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| Formula = KCl
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| MolarMass = 74.5513 g/mol
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| MeltingPtC = 770
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| pKa = ~7
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| Solubility = 35.5 g/100 ml (20 °C)
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| SolubleOther = Soluble in alkali, [[glycerol]]<br>Slightly soluble in [[alcohol]]<br>Insoluble in [[diethyl ether]]
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| DeltaHf = −436 kJ/mol
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| Entropy = 83 J·mol<sup>−1</sup>·K<sup>−1</sup>
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'''Potassium chloride''' is a salt with the formula '''KCl'''. It is a white crystalline solid. It is edible, commonly used as a salt substitute, but it has a sharp, biting aftertaste (which is often described as metallic) that many people find unpleasant.
 
'''Potassium chloride''' is a salt with the formula '''KCl'''. It is a white crystalline solid. It is edible, commonly used as a salt substitute, but it has a sharp, biting aftertaste (which is often described as metallic) that many people find unpleasant.
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[[File:Sol_curve.jpg|thumb|200px|Solubility chart]]
 
  
 
==Properties==
 
==Properties==
 
===Physical===
 
===Physical===
 
Potassium chloride is a white crystalline solid with a cubic structure. It has a molar mass of 74.55. Its solubility in water is 28g/100mL at 0˚C and 56.7g/mL at 100˚C<ref>CRC Handbook of Chemistry and Physics 66th edition</ref>
 
Potassium chloride is a white crystalline solid with a cubic structure. It has a molar mass of 74.55. Its solubility in water is 28g/100mL at 0˚C and 56.7g/mL at 100˚C<ref>CRC Handbook of Chemistry and Physics 66th edition</ref>
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[[File:Sol_curve.jpg|thumb|200px|Solubility chart]]
  
 
===Chemical===
 
===Chemical===
 
Potassium chloride can be used as a source of chloride ions in reactions, although sodium chloride is more common. KCl is often used to make KClO<sub>3</sub> ([[Potassium chlorate|potassium chlorate]]) using electrolysis. The high solubility of KCl at low temperature compared to KClO<sub>3</sub> makes it easy to separate the two compounds from a solution.
 
Potassium chloride can be used as a source of chloride ions in reactions, although sodium chloride is more common. KCl is often used to make KClO<sub>3</sub> ([[Potassium chlorate|potassium chlorate]]) using electrolysis. The high solubility of KCl at low temperature compared to KClO<sub>3</sub> makes it easy to separate the two compounds from a solution.
  
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[[File:Potassium_chloride_salt_substitute.jpg|thumb|120px|Potassium chloride salt substitute]]
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[[File:Potassium_chloride_salt_substitute by Zts16.jpg|thumb|120px|Potassium chloride salt substitute]]
  
 
==Availability==
 
==Availability==

Revision as of 17:30, 3 April 2017

Potassium chloride
Potassium chloride.jpg
Names
IUPAC name
Potassium chloride
Other names
Muriate of potash
Sylvite
Properties
KCl
Molar mass 74.5513 g/mol
Appearance White solid
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)
35.5 g/100 ml (20 °C)
Solubility Soluble in alkali, glycerol
Slightly soluble in alcohol
Insoluble in diethyl ether
Vapor pressure ~0
Acidity (pKa) ~7
Thermochemistry
83 J·mol−1·K−1
−436 kJ/mol
Hazards
Lethal dose or concentration (LD, LC):
2600 mg/kg (rat, oral)
Related compounds
Related compounds
 Sodium chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Potassium chloride is a salt with the formula KCl. It is a white crystalline solid. It is edible, commonly used as a salt substitute, but it has a sharp, biting aftertaste (which is often described as metallic) that many people find unpleasant.

Properties

Physical

Potassium chloride is a white crystalline solid with a cubic structure. It has a molar mass of 74.55. Its solubility in water is 28g/100mL at 0˚C and 56.7g/mL at 100˚C[1]

Solubility chart

Chemical

Potassium chloride can be used as a source of chloride ions in reactions, although sodium chloride is more common. KCl is often used to make KClO3 (potassium chlorate) using electrolysis. The high solubility of KCl at low temperature compared to KClO3 makes it easy to separate the two compounds from a solution.

Potassium chloride salt substitute

Availability

Potassium chloride can be easily obtained in relatively pure form at the grocery store as a salt substitute for people with low-sodium diets. This source is mixed in with potassium bitartarate to improve taste. However, salt substitute is deliberately overpriced by the companies that make it; it is many times cheaper to obtain potassium chloride through other means, often through larger industrial quantities, which are usually purer anyway. This includes buying potassium chloride as fertilizer, sometimes referred to as muriate of potash. In some hardware stores, sodium-free water purification tablets made of 99% or higher potassium chloride can be purchased, usually in bags weighing about 40 lbs. These are by far the most economic method of purchasing potassium chloride.

Preparation

Potassium chloride can be prepared from potassium hydroxide and hydrochloric acid, but this method is uneconomical in the lab due to the fact that KCl is usually easier to get than potassium hydroxide. Potassium carbonate or potassium bicarbonate can also be added to hydrochloric acid, but this requires care to control carbon dioxide outgassing.

Projects

Handling

Safety

No safety measures are needed with potassium chloride. It is non-toxic unless directly consumed in very large quantities.

Storage

Potassium chloride should be stored in closed bottles. No special storage is required.

Disposal

Potassium chloride can be safely poured down the drain.

References

  1. ↑ CRC Handbook of Chemistry and Physics 66th edition

Relevant Sciencemadness threads

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