Potassium chloride

Potassium chloride ;
Names:	potassium chloride; muriate of potash; MOP; Е508 food additive;
Formula:	KCl;
Molar mass:	74.551 g/mol;
Density:	1.988 g/cm3;
Crystal system:	cubic; a=6.29294 Å, b=6.29294 Å, c=6.29294 Åα=90°, β=90°, γ=90°;
Shapes:	https://en.crystalls.info/w/uploads/media/f/f1/Cube.json Cube https://en.crystalls.info/w/uploads/media/a/af/Tetragonal_prism.json Tetragonal prism https://en.crystalls.info/w/uploads/media/3/30/Tetragonal_flat_prism.json Tetragonal flat prism https://en.crystalls.info/w/uploads/media/c/c4/Tetragonal_pedion.json Tetragonal pedion https://en.crystalls.info/w/uploads/media/5/52/Needle.json Needle ;
Color:	colorless;
Melting point:	776 °C1,049.15 K <br />1,428.8 °F <br />1,888.47 °R <br />;
Boiling point:	1420 °C1,693.15 K <br />2,588 °F <br />3,047.67 °R <br />;
Refractive index:	1.4902 ;
Magnetic properties:	diamagnetic; χ=-3.90 · 10-5cm³/mol;
Radiation properties:	slightly radioactive;
Stability:	stable;
Hardness:	strong; (2.5 on Moh's scale);
Toxicity:	non-toxic; LD50=2600mg/kg

Description

Inorganic compound, salt of alkaline metal potassium and inorganic hydrochloric acid. Doesn't form water hydrates.

Minerals

Occurs in nature as sylvite, sylvinite and carnallite minerals.

Where to buy

Can be bought in fertilizers store (as "muriate of potash").

Precursors

Reaction between potassium hydroxide or carbonate and hydrochloric acid

Chemical equation:

HCl + KOH = KCl + H₂O

2HCl + K₂CO₃ = 2KCl + H₂O + CO₂↑

For preparation of 100.00g of potassium chloride а 75.26g of potassium hydroxide or 92.69g of carbonate and 128.70g of 38%38% hydrochloric acid is required.

Add acid to the flask, then add small parts of potassium compound with stirring until it will totally dissolve or, if you use carbonate, until carbon dioxide emission will stop. After reaction will stop, filter the solution and use it for crystal growing.

Recrystallization of "salt with a lower sodium content"

Add potassium and sodium chlorides mixture to the flask with boiling water until solution become saturated. Then filter out the solution and cool slowly. Excess of potassium chloride forms a crystalline precipitate, when most of impurities remain in the solution.

Separate this precipitate from the stock solution, add another portion of mixture, and repeat this process several times, using the same solution again and again. Finally, the precipitated potassium chloride is used for crystal growing, and solution with accumulated impurities is thrown away.

Influence of temperature

Temperature increase leads to changing crystals shape to long thin needles.

Temperature	g/`100,00` g water	g/`100,00` g ethanol	g/`100,00` g methanol	g/`100,00` g glycerol	g/`100,00` g furfural	g/`100,00` g ethylene glycol	g/`100,00` g formic acid 95%	g/`100,00` g acetic acid	g/`100,00` g propanol	g/`100,00` g hydrazine	g/`100,00` g acetamide	g/`100,00` g dimethylformamide	g/`100,00` g N-methylformamide	g/`100,00` g formamide
0°C273.15 K <br />32 °F <br />491.67 °R <br />	`27.78`
10°C283.15 K <br />50 °F <br />509.67 °R <br />	`30.91`
15°C288.15 K <br />59 °F <br />518.67 °R <br />		`0.0265`
20°C293.15 K <br />68 °F <br />527.67 °R <br />	`34.03`						`19.4`	`0.195`		`9`
25°C298.15 K <br />77 °F <br />536.67 °R <br />	`36.01`	`0.0288`	`0.54`	`6.7`	`0.073`	`5.18`			`0.004`		`2.45`	`0.05`	`2.1`	`6.2`
30°C303.15 K <br />86 °F <br />545.67 °R <br />	`37.47`		`0.56`
40°C313.15 K <br />104 °F <br />563.67 °R <br />	`40.31`	`0.0325`	`0.60`
50°C323.15 K <br />122 °F <br />581.67 °R <br />	`43.05`	`0.039`	`0.63`
60°C333.15 K <br />140 °F <br />599.67 °R <br />	`45.64`		`0.67`					`0.285`
70°C343.15 K <br />158 °F <br />617.67 °R <br />	`48.33`
80°C353.15 K <br />176 °F <br />635.67 °R <br />	`50.85`	`0.049`
90°C363.15 K <br />194 °F <br />653.67 °R <br />	`53.82`							`0.457`
100°C373.15 K <br />212 °F <br />671.67 °R <br />	`56.37`

Slightly soluble in pyridine. Insoluble in acetone, acetonitrile and amyl alcohol.

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Chlorides
Salts	Ammonium chloride (NH₄Cl) • Barium chloride (BaCl₂) • Calcium chloride (CaCl₂) • Cadmium chloride (CdCl₂) • Cobalt(II) chloride (CoCl₂) • Copper(II) chloride (CuCl₂) • Iron(II) chloride (FeCl₂) • Iron(III) chloride (FeCl₃) • Lead(II) chloride (PbCl) • Manganese(II) chloride (MnCl₂) • Potassium chloride (KCl) • Sodium chloride (NaCl) • Strontium chloride (SrCl₂) • Tin(II) chloride (SnCl₂) • Zirconyl chloride (ZrOCl₂)
Double salts	Rubidium-gold(III)-palladium(II) chloride (2RbCl · AuCl₃ · PdCl₂)
Adducts	Diglycine hydrochloride (2NH₂CH₂COOH · HCl) • Glutamic acid hydrochloride (C₅H₉NO₄ · HCl) • Glucose and sodium chloride complex (2C₆H₁₂O₆ · NaCl) • Hydroxylammonium chloride (NH₂OH · HCl) • P-nitroaniline hydrochloride (C₆H₆N₂O₂ · HCl) • Urea and sodium chloride complex (CO(NH₄)₂ · NaCl)
Complexes	Ammonium pentachloroferrate(III) ((NH₄)₂[FeCl₅]) • Ammonium tetrachlorocuprate(II) ((NH₄)₂[CuCl₄]) • Lithium trioxalatoferrate(III)-chloride (Li₄[Fe(C₂O₄)₃]Cl) • Hexamminecobalt(III) chloride ([Co(NH₃)₆]Cl₂) • Hexaamminenickel chloride ([Ni(NH₃)₆]Cl₂) • Potassium hexachlororhodate(III) (K₃[RhCl₆])

Potassium compounds
Salts	Potassium bromate (KBrO₃) • Potassium bromide (KBr) • Potassium chlorate (KClO₃) • Potassium chloride (KCl) • Potassium chromate (K₂CrO₄) • Potassium dihydrophosphate (KH₂PO₄) • Potassium dichromate (K₂Cr₂O₇) • Potassium iodide (KI) • Potassium hydrofluoride (KHF₂) • Potassium hydrophosphate (K₂HPO₄) • Potassium hydrophthalate (KC₈H₆O₄) • Potassium metavanadate (KVO₃) • Potassium nitrate (KNO₃) • Potassium sulfate (K₂SO₄) • Potassium thiocyanate (KNCS)
Double salts	Aluminum-potassium sulfate (KAl(SO₄)₂) • Antimony(III)-potassium tartrate (K₂Sb₂(C₄H₂O₆)₂) • Chromium(III)-potassium sulfate (KCr(SO₄)₂) • Cobalt(II)-potassium sulfate (K₂Co(SO₄)₂) • Copper(II)-potassium sulfate (K₂Cu(SO₄)₂) • Indium(III)-potassium sulfate (KIn(SO₄)₂) • Iron(II)-potassium sulfate (K₂Fe(SO₄)₂) • Iron(III)-potassium sulfate (KFe(SO₄)₂) • Lithium-potassium sulfate (KLiSO₄) • Magnesium-potassium sulfate (K₂Mg(SO₄)₂) • Magnesium-potassium sulfate-chromate (K₂CrO₄ · MgSO₄) • Manganese(II)-potassium sulfate (K₂Mn(SO₄)₂) • Nickel-potassium sulfate (K₂Ni(SO₄)₂) • Potassium-sodium tartrate (KNaC₄H₄O₆) • Vanadium(III)-ammonium sulfate (NH₄V(SO₄)₂) • Zinc-potassium sulfate (K₂Zn(SO₄)₂)
Complexes	Potassium dioxalatocuprate(II) (K₂[Cu(C₂O₄)₂]) • Potassium hexanitrocobaltate(III) (K₃[Co(NO₂)₆]) • Potassium hexachlororhodiate(III) (K₃[RhCl₆]) • Potassium hexacyanocobaltate(III) (K₃[Co(CN)₆]) • Potassium hexacyanoferrate(II) (K₄[Fe(CN)₆]) • Tripotassium-sodium hexacyanoferrate(II) (K₃Na[Fe(CN)₆]) • Potassium hexacyanoferrate(III) (K₃[Fe(CN)₆]) • Potassium hexacyanochromate(III) (K₃[Co(CN)₆]) • Potassium tetraiodobismuthate (К[BiI₄]) • Potassium tetraiodomercurate(II) (K₂[HgI₄]) • Potassium trioxalatoaluminate (K₃[Al(C₂O₄)₃]) • Potassium trioxalatocobaltate(III) (K₃[Co(C₂O₄)₃]) Potassium trioxalatoferrate(III) (K₃[Fe(C₂O₄)₃]) • Potassium-sodium trioxalatoferrate(III) (K₅Na[Fe(C₂O₄)₃]₂) • Dipotassium-sodium trioxalatoferrate(III) (K₂Na[Fe(C₂O₄)₃]) • Potassium trioxalatochromate(III) (K₃[Cr(C₂O₄)₃])

Potassium chloride
Names:	potassium chloride muriate of potash MOP Е508 food additive
Formula:	KCl
Molar mass:	74.551 g/mol
Density:	1.988 g/cm³
Crystal system:	cubic a=6.29294 Å, b=6.29294 Å, c=6.29294 Åα=90°, β=90°, γ=90°
Shapes:	Cube Tetragonal prism Tetragonal flat prism Tetragonal pedion Needle
Color:	colorless
Melting point:	776 °C1,049.15 K <br />1,428.8 °F <br />1,888.47 °R <br />
Boiling point:	1420 °C1,693.15 K <br />2,588 °F <br />3,047.67 °R <br />
Refractive index:	1.4902
Magnetic properties:	diamagnetic χ=-3.90 · 10^-5cm³/mol
Radiation properties:	slightly radioactive
Stability:	stable
Hardness:	strong (2.5 on Moh's scale)
Toxicity:	non-toxic LD₅₀=2600mg/kg