Potassium sulfate

Potassium sulfate ;
Names:	potassium sulfate; dipotassium sulfate; Е515 food additive;
Formula:	K2SO4;
Molar mass:	174.257 g/mol;
Density:	2.663 g/cm3;
Crystal system:	orthorhombic (α); a=5.7704 Å, b=10.0712 Å, c=7.4776 Åα=90°, β=90°, γ=90°; hexagonal (β); a=5.947 Å, b=5.947 Å, c=8.375 Åα=90°, β=90°, γ=120°;
Shapes:	https://en.crystalls.info/w/uploads/media/c/c4/Hexagonal_bipyramid.json Hexagonal bipyramid https://en.crystalls.info/w/uploads/media/5/52/Hexagonal_pyramid.json Hexagonal pyramid https://en.crystalls.info/w/uploads/media/3/35/Deformed_tetragonal_bipyramid.json Deformed tetragonal bipyramid ;
Color:	colorless;
Melting point:	1069 °C1,342.15 K <br />1,956.2 °F <br />2,415.87 °R <br />;
Boiling point:	1689 °C1,962.15 K <br />3,072.2 °F <br />3,531.87 °R <br />;
Decomposition point:	583 °C856.15 K <br />1,081.4 °F <br />1,541.07 °R <br /> (α);
Refractive index:	1.495 ;
Magnetic properties:	diamagnetic; χ=-6.70 · 10-5cm³/mol;
Stability:	stable;
Hardness:	relatively strong; (2 on Moh's scale);
Toxicity:	non-toxic; LD50=6600mg/kg

Description

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

Where to buy

Can be bought in fertilizers store (as "Potassium sulfate").

Precursors

Reaction between hydroxide or potassium carbonate and sulfuric acid

Chemical equation:

H₂SO₄ + 2KOH = K₂SO₄ + 2H₂O

H₂SO₄ + K₂CO₃ = K₂SO₄ + H₂O + CO₂↑

For preparation of 100.00g of potassium sulfate а 64.39g of hydroxide or 79.31g of carbonate and 152.12g of 37%37% sulfuric 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 "Potassium sulfate" fertilizer

Add fertilizer to the flask with boiling water until solution become saturated. Then filter out the solution and cool slowly. Excess of potassium sulfate 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 sulfate is used for crystal growing, and solution with accumulated impurities is thrown away.

Due to potassium carbonate impurity in fertilizer, it is recommended to add sulfuric acid to fertilizer solution before recrystallization.

Reaction between potassium chloride or nitrate and ammonium nitrate

Chemical equation:

(NH₄)₂SO₄ + KCl = K₂SO₄↓ + 2NH₄Cl

(NH₄)₂SO₄ + KNO₃ = K₂SO₄↓ + 2NH₄NO₃

For preparation of 100.00g of potassium sulfate а 42.78g of potassium chloride or 58.02g of potassium nitrate and 75.83g of ammonium sulfate is required.

Add to the flask with hot ammonium sulfate solution a potassium chloride or nitrate solution with stirring. Cooling this mixture will cause forming a large amount of crystalline precipitate. Filter precipitate and wash it wish small amount of cold water, then filter the solution and use it for crystal growing.

Reaction between potassium chloride or nitrate and sulfuric acid

Chemical equation:

H₂SO₄ + 2KCl = K₂SO₄ + 2HCl↑

H₂SO₄ + 2KNO₃ = K₂SO₄ + 2HNO₃↑

For preparation of 100.00g of potassium sulfate а 85.56g of potassium chloride or 116.04g of potassium nitrate and 152.12g of

37%37%
70%

sulfuric acid is required.

Add to the flask acid and then add small parts of hot acid solution with heating and stirring. Emission of large amount of gas will begin.Attention, exuding gas irritates eyes and lungs! The synthesis should be carried out only in a fume hood or outdoors! After reaction will stop, filter the solution and use it for crystal growing.

Reaction between ammonium sulfate and potassium hydroxide or carbonate

Chemical equation:

(NH₄)₂SO₄ + 2KOH = K₂SO₄ + 2H₂O + 2NH₃↑

(NH₄)₂SO₄ + K₂CO₃ = K₂SO₄ + H₂O + CO₂↑ + 2NH₃↑

For preparation of 100.00g of potassium sulfate а 64.39g of potassium hydroxide or 79.31g of carbonate and 75.83g of ammonium sulfate is required.

Add to the flask saturated solution of ammonium sulfate and then add small parts of hot potassium compounds solution with heating and stirring. Emission of large amount of ammonia will begin.Attention, exuding ammonia irritates eyes and lungs! The synthesis should be carried out only in a fume hood or outdoors! After reaction will stop, filter the solution and use it for crystal growing.

Notes

Used as a substratum for microbes and fungi, so mold can grow easily in the solution. It is recommended to boil solution for 15 minutes and change vessel to another one.

Storage conditions

Keep in its original form or under several layers of varnish at average humidity and room temperature. Do not keep crystals near heaters.

Solubility

TableGraph

Temperature	g/`100,00` g water	g/`100,00` g ethanol 40%	g/`100,00` g methanol	g/`100,00` g glycerol	g/`100,00` g formic acid 95%	g/`100,00` g sulfuric acid	g/`100,00` g hydrazine	g/`100,00` g hydroxylamine
0°C273.15 K <br />32 °F <br />491.67 °R <br />	`7.18`
10°C283.15 K <br />50 °F <br />509.67 °R <br />	`9.3`
20°C293.15 K <br />68 °F <br />527.67 °R <br />	`11.1`			`1.317`	`36.5`		`5`	`3.5`
25°C298.15 K <br />77 °F <br />536.67 °R <br />	`12.1`		`0.0596`
30°C303.15 K <br />86 °F <br />545.67 °R <br />	`13`
40°C313.15 K <br />104 °F <br />563.67 °R <br />	`14.8`	`0.16`				`11.61`
60°C333.15 K <br />140 °F <br />599.67 °R <br />	`18.2`
70°C343.15 K <br />158 °F <br />617.67 °R <br />	`19.9`
80°C353.15 K <br />176 °F <br />635.67 °R <br />	`21.4`
90°C363.15 K <br />194 °F <br />653.67 °R <br />	`22.9`
100°C373.15 K <br />212 °F <br />671.67 °R <br />	`24.1`					`41.42`

Slightly soluble in glycerol. Insoluble in ethanol, acetone, benzene, carbon disulfide, ethylene glycol and ammonia.

Gallery

Growth during 3 weeksPotassium sulfate, Maxim Martinov, VKontakteMaxim MartinovVKontakte
Growth during 3 weeksPotassium sulfate, Maxim Martinov, VKontakteMaxim MartinovVKontakte
Growth during 2 monthsPotassium sulfate, Maxim Martinov, VKontakteMaxim MartinovVKontakte
Growth during 2 monthsPotassium sulfate, Maxim Martinov, VKontakteMaxim MartinovVKontakte
Growth during 3 monthsPotassium sulfate, Maxim Martinov, VKontakteMaxim MartinovVKontakte
Growth during 3 monthsPotassium sulfate, Maxim Martinov, VKontakteMaxim MartinovVKontakte
Growth during several monthPotassium sulfate, Dmitry Shintyakov, VKontakteDmitry ShintyakovVKontakte
Growth during several monthPotassium sulfate, Dmitry Shintyakov, VKontakteDmitry ShintyakovVKontakte

Video

Sources

Sulfates
Simple	Aluminum sulfate (Al₂(SO₄)₃) • Ammonium sulfate ((NH₄)₂SO₄) • Calcium sulfate (CaSO₄) • Cadmium sulfate (CdSO₄) • Cerium(III) sulfate (Ce₂(SO₄)₃) • Cerium(IV) sulfate (Ce(SO₄)₂) • Chromium(III) sulfate (Cr₂(SO₄)₃) • Cobalt(II) sulfate (CoSO₄) • Copper(II) sulfate (CuSO₄) • Gadolinium sulfate (Gd₂(SO₄)₃) • Holmium sulfate (Ho₂(SO₄)₃) • Hydrazine sulfate (N₂H₄ · H₂SO₄) • Iron(II) sulfate (FeSO₄) • Iron(III) sulfate (Fe₂(SO₄)₃) • Lanthanum sulfate (La₂(SO₄)₃) • Lithium sulfate (Li₂SO₄) • Magnesium sulfate (MgSO₄) • Manganese(II) sulfate (MnSO₄) • Neodymium sulfate (Nd₂(SO₄)₃) • Nickel sulfate (NiSO₄) • Potassium sulfate (K₂SO₄) • Praseodymium(III) sulfate (Pr₂(SO₄)₃) • Rubidium sulfate (Rb₂SO₄) • Sodium hydrosulfate (NaHSO₄) • Sodium sulfate (Na₂SO₄) • Yttrium sulfate (Gd₂(SO₄)₃) • Zinc sulfate (ZnSO₄)
Alums	Aluminum-ammonium sulfate (NH₄Al(SO₄)₂) • Aluminum-potassium sulfate (KAl(SO₄)₂) • Chromium(III)-ammonium sulfate (NH₄Cr(SO₄)₂) • Chromium(III)-potassium sulfate (KCr(SO₄)₂) • Cobalt(III)-ammonium sulfate (NH₄Co(SO₄)₂) • Indium(III)-potassium sulfate (KIn(SO₄)₂) • Iron(III)-ammonium sulfate (NH₄Fe(SO₄)₂) • Iron(III)-potassium sulfate (KFe(SO₄)₂) • Manganese(III)-ammonium sulfate (NH₄Mn(SO₄)₂) • Vanadium(III)-ammonium sulfate (NH₄V(SO₄)₂)
Tutton's salts	Chromium(II)-ammonium sulfate ((NH₄)₂Cr(SO₄)₂) • Cobalt(II)-ammonium sulfate ((NH₄)₂Co(SO₄)₂) • Cobalt(II)-potassium sulfate (K₂Co(SO₄)₂) • Copper(II)-ammonium sulfate ((NH₄)₂Cu(SO₄)₂) • Copper(II)-potassium sulfate (K₂Cu(SO₄)₂) • Iron(II)-ammonium sulfate ((NH₄)₂Fe(SO₄)₂) • Iron(II)-potassium sulfate (K₂Fe(SO₄)₂) • Magnesium-ammonium sulfate ((NH₄)₂Mg(SO₄)₂) • Magnesium-potassium sulfate (K₂Mg(SO₄)₂) • Magnesium-potassium sulfate-chromate (K₂CrO₄ · MgSO₄) • Manganese(II)-ammonium sulfate ((NH₄)₂Mn(SO₄)₂) • Manganese(II)-potassium sulfate (K₂Mn(SO₄)₂) • Nickel-ammonium sulfate ((NH₄)₂Ni(SO₄)₂) • Nickel-potassium sulfate (K₂Ni(SO₄)₂) • Vanadium(II)-ammonium sulfate ((NH₄)₂V(SO₄)₂) • Zinc-ammonium sulfate ((NH₄)₂Zn(SO₄)₂) • Zinc-potassium sulfate (K₂Zn(SO₄)₂)
Double salts	Copper(II)-iron(II) sulfate ((Cu,Fe)SO₄) • Iron(II)-magnesium sulfate ((Fe,Mg)SO₄) • Lithium-potassium sulfate (KLiSO₄) • Sodium-ammonium sulfate (NaNH₄SO₄) • Zinc-sodium sulfate (Na₂Zn(SO₄)₂)
Adducts	Triglycine sulfate ((NH₂CH₂COOH)₃ · H₂SO₄) • Glutamic acid sulfate (C₅H₉NO₄ · H₂SO₄)
Complexes	Cerium(III) sulfocerate(IV) (Ce₄[Ce(SO₄)₄]₃) • Glycinecopper(II) sulfate ([Cu(NH₂CH₂COOH)]SO₄) • Hexakarbamatzinc sulfate ([(CON₂H₄)₆Zn]SO₄) • Tetraamminecopper(II) sulfate ([Cu(NH₃)₄]SO₄) • Tris(hydroxymethil)methanoaminecopper(II) sulfate ([Cu(NH₂C(CH₂OH)₃)₄]SO₄)

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 hydrogen phthalate (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 sulfate
Names:	potassium sulfate dipotassium sulfate Е515 food additive
Formula:	K₂SO₄
Molar mass:	174.257 g/mol
Density:	2.663 g/cm³
Crystal system:	orthorhombic (α) a=5.7704 Å, b=10.0712 Å, c=7.4776 Åα=90°, β=90°, γ=90° hexagonal (β) a=5.947 Å, b=5.947 Å, c=8.375 Åα=90°, β=90°, γ=120°
Shapes:	Hexagonal bipyramid Hexagonal pyramid Deformed tetragonal bipyramid
Color:	colorless
Melting point:	1069 °C1,342.15 K <br />1,956.2 °F <br />2,415.87 °R <br />
Boiling point:	1689 °C1,962.15 K <br />3,072.2 °F <br />3,531.87 °R <br />
Decomposition point:	583 °C856.15 K <br />1,081.4 °F <br />1,541.07 °R <br /> (α)
Refractive index:	1.495
Magnetic properties:	diamagnetic χ=-6.70 · 10^-5cm³/mol
Stability:	stable
Hardness:	relatively strong (2 on Moh's scale)
Toxicity:	non-toxic LD₅₀=6600mg/kg

Potassium sulfate

Description

Minerals

Where to buy

Precursors

Reaction between hydroxide or potassium carbonate and sulfuric acid

Recrystallization of "Potassium sulfate" fertilizer

Reaction between potassium chloride or nitrate and ammonium nitrate

Reaction between potassium chloride or nitrate and sulfuric acid

Reaction between ammonium sulfate and potassium hydroxide or carbonate

Notes

Storage conditions

Solubility

Gallery

Video

Sources

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