Trisodium phosphate

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Trisodium phosphate [1]
Trisodium phosphate, Trisodium phosphate.png
Trisodium phosphate,
Trisodium phosphate 3D.jpg
Trisodium phosphate hydrate.jpg
IUPAC name
Trisodium phosphate
Other names
Sodium phosphate tribasic, trisodium orthophosphate, sodium phosphate
3D model (JSmol)
ECHA InfoCard 100.028.645 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 231-509-8
E number E339(iii) (antioxidants, ...)
PubChem CID
RTECS number
  • InChI=1S/3Na.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3*+1;/p-3 Yes check.svgY
  • InChI=1/3Na.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3*+1;/p-3
  • [O-]P(=O)([O-])[O-].[Na+].[Na+].[Na+]
Molar mass 163.939 g·mol−1
Density 2.536 g/cm3 (17.5 °C, anhydrous)
1.62 g/cm3 (20 °C, dodecahydrate) [2] [3] [4]
Melting point 1,583 °C (2,881 °F; 1,856 K)
(anhydrous) [3]
73.4 °C (164.1 °F; 346.5 K)
(dodecahydrate) [4]
Boiling point 100 °C (212 °F; 373 K)(dodecahydrate) decomposes [4]
anhydrous: [3]
5.4 g/100 mL (0 °C)
12 g/100 mL (20 °C) [5]
14.5 g/100 mL (25 °C)
23.3 g/100 mL (40 °C)
94.6 g/100 mL (100 °C)
dodecahydrate: [4]
28.3 g/100 mL (20 °C)
Solubility insoluble in ethanol, CS2 [4]
Basicity (pKb)2.23
665 J/mol·K (dodecahydrate) [4]
224.7 J/mol·K (anhydrous) [3]
660 J/mol·K (dodecahydrate) [4]
-1935.5 kJ/mol (anhydrous) [3]
-5480 kJ/mol (dodecahydrate) [4]
-1819 kJ/mol (anhydrous) [3]
A06AD17 ( WHO ) A06AG01 ( WHO ) B05XA09 ( WHO )
Hazards [6]
GHS labelling:
GHS-pictogram-acid.svg GHS-pictogram-exclam.svg
H315, H318, H335
P261, P280, P305+P351+P338
NFPA 704 (fire diamond)
Flash point Non-flammable
Safety data sheet (SDS) ICSC 1178
Related compounds
Other cations
Tripotassium phosphate
Triammonium phosphate
Trimagnesium phosphate
Related compounds
Monosodium phosphate
Disodium phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Trisodium phosphate (TSP) is the inorganic compound with the chemical formula Na3 PO4 . It is a white, granular or crystalline solid, highly soluble in water, producing an alkaline solution. TSP is used as a cleaning agent, builder, lubricant, food additive, stain remover, and degreaser. [7]

The item of commerce is often partially hydrated and may range from anhydrous Na3PO4 to the dodecahydrate Na3PO4· 12 H2O . Most often found in white powder form, it can also be called trisodium orthophosphate or simply sodium phosphate.


Trisodium phosphate is produced by neutralization of phosphoric acid using sodium carbonate, which produces disodium hydrogen phosphate. The disodium hydrogen phosphate is reacted with sodium hydroxide to form trisodium phosphate and water.

Na2CO3 + H3PO4 → Na2HPO4 + CO2 + H2O
Na2HPO4 + NaOH → Na3PO4 + H2O



Trisodium phosphate was at one time extensively used in formulations for a variety of consumer-grade soaps and detergents, and the most common use for trisodium phosphate has been in cleaning agents. The pH of a 1% solution is 12 (i.e., very basic), and the solution is sufficiently alkaline to saponify grease and oils. In combination with surfactants, TSP is an excellent agent for cleaning everything from laundry to concrete driveways. This versatility and low manufacturing price made TSP the basis for a plethora of cleaning products sold in the mid-20th century.

TSP is still sold and used as a cleaning agent, but since the late 1960s, its use has diminished in the United States and many other parts of the world because, like many phosphate-based cleaners, it is known to cause extensive eutrophication of lakes and rivers once it enters a water system. [8]

TSP is commonly used after cleaning a surface with mineral spirits to remove hydrocarbon residues and may be used with household chlorine bleach in the same solution without hazardous reactions.[ citation needed ] This mixture is particularly effective for removing mildew, but is less effective at removing mold.[ citation needed ]

Although it is still the active ingredient in some toilet bowl-cleaning tablets, TSP is generally not recommended for cleaning bathrooms because it can stain metal fixtures and can damage grout. [9]


With the formula Na3PO4· 1/4NaOCl · 11 H2O the material called chlorinated trisodium phosphate is used as a disinfectant and bleach, like sodium hypochlorite. It is prepared using NaOCl in place of some of the base to neutralize phosphoric acid. [7]


In the U.S., trisodium phosphate is an approved flux for use in hard soldering joints in medical-grade copper plumbing. The flux is applied as a concentrated water solution and dissolves copper oxides at the temperature used in copper brazing. Residues are water-soluble and can be rinsed out before plumbing is put into service.

TSP is used as an ingredient in fluxes designed to deoxygenate nonferrous metals for casting. It can be used in ceramic production to lower the flow point of glazes.

Painting enhancement

TSP is still in common use for the cleaning, degreasing, and deglossing of walls prior to painting. TSP breaks the gloss of oil-based paints and opens the pores of latex-based paint, providing a surface better suited for the adhesion of the subsequent layer. [10] [ unreliable source? ]

Food additive

Sodium phosphates including monosodium phosphate, disodium phosphate, and trisodium phosphate are approved as food additives in the EU. They are commonly used as acidity regulators and have the collective E number E339. [11] The United States Food and Drug Administration lists sodium phosphates as generally recognized as safe. [12] [13]

Exercise performance enhancement

Trisodium phosphate has gained a following as a nutritional supplement that can improve certain parameters of exercise performance. [14] The basis of this belief is the fact that phosphate is required for the energy-producing Krebs cycle central to aerobic metabolism. Phosphates are available from a number of other sources that are much milder than TSP. While TSP is not toxic per se, it is severely irritating to gastric mucosa unless used as part of a buffered solution.


In the Western world, phosphate usage has declined owing to ecological problems with the damage to lakes and rivers through eutrophication.


By the end of the 20th century, many products that formerly contained TSP were manufactured with TSP substitutes, which consist mainly of sodium carbonate along with various admixtures of nonionic surfactants and a limited percentage of sodium phosphates.

Products sold as TSP substitutes, containing soda ash and zeolites, are promoted as direct substitutes. However, sodium carbonate is not as strongly basic as trisodium phosphate, making it less effective in demanding applications.[ citation needed ] Zeolites, which are clay based, are added to laundry detergents as water softening agents and are essentially non-polluting; however, zeolites do not dissolve and can deposit a fine, powdery residue in the wash tub.[ citation needed ] Cleaning products labeled as TSP may contain other ingredients, with perhaps less than 50% trisodium phosphate. [15]

Related Research Articles

Phosphate Chemical compound

In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid H

Pyrophosphate Chemical compound

In chemistry, pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a P–O–P linkage. A number of pyrophosphate salts exist, such as disodium pyrophosphate (Na2H2P2O7) and tetrasodium pyrophosphate (Na4P2O7), among others. Often pyrophosphates are called diphosphates. The parent pyrophosphates are derived from partial or complete neutralization of pyrophosphoric acid. The pyrophosphate bond is also sometimes referred to as a phosphoanhydride bond, a naming convention which emphasizes the loss of water that occurs when two phosphates form a new P–O–P bond, and which mirrors the nomenclature for anhydrides of carboxylic acids. Pyrophosphates are found in ATP and other nucleotide triphosphates, which are very important in biochemistry.

Phosphoric acid Chemical compound

Phosphoric acid, is a weak acid with the chemical formula H
. The pure compound is a colorless solid.

Sodium hexametaphosphate Chemical compound

Sodium hexametaphosphate (SHMP) is a salt of composition Na6[(PO3)6]. Sodium hexametaphosphate of commerce is typically a mixture of metaphosphates (empirical formula: NaPO3), of which the hexamer is one, and is usually the compound referred to by this name. Such a mixture is more correctly termed sodium polymetaphosphate. They are white solids that dissolve in water.

Trisodium citrate Chemical compound

Trisodium citrate has the chemical formula of Na3C6H5O7. It is sometimes referred to simply as "sodium citrate", though sodium citrate can refer to any of the three sodium salts of citric acid. It possesses a saline, mildly tart flavor, and is a mild alkali.

Sodium triphosphate Chemical compound

Sodium triphosphate (STP), also sodium tripolyphosphate (STPP), or tripolyphosphate (TPP),) is an inorganic compound with formula Na5P3O10. It is the sodium salt of the polyphosphate penta-anion, which is the conjugate base of triphosphoric acid. It is produced on a large scale as a component of many domestic and industrial products, especially detergents. Environmental problems associated with eutrophication are attributed to its widespread use.

Sodium phosphate is a generic term for a variety of salts of sodium (Na+) and phosphate (PO43−). Phosphate also forms families or condensed anions including di-, tri-, tetra-, and polyphosphates. Most of these salts are known in both anhydrous (water-free) and hydrated forms. The hydrates are more common than the anhydrous forms.

Tetrasodium pyrophosphate Chemical compound

Tetrasodium pyrophosphate, also called sodium pyrophosphate, tetrasodium phosphate or TSPP, is an inorganic compound with the formula Na4P2O7. As a salt, it is a white, water-soluble solid. It is composed of pyrophosphate anion and sodium ions. Toxicity is approximately twice that of table salt when ingested orally. Also known is the decahydrate Na4P2O7 · 10(H2O).

Diammonium phosphate Chemical compound

Diammonium phosphate (DAP; IUPAC name diammonium hydrogen phosphate; chemical formula (NH4)2(HPO4) is one of a series of water-soluble ammonium phosphate salts that can be produced when ammonia reacts with phosphoric acid.

Phosphoric acids and phosphates

A phosphoric acid, in the general sense, is a phosphorus oxoacid in which each phosphorus (P) atom is in the oxidation state +5, and is bonded to four oxygen (O) atoms, one of them through a double bond, arranged as the corners of a tetrahedron. Two or more of these PO
tetrahedra may be connected by shared single-bonded oxygens, forming linear or branched chains, cycles, or more complex structures. The single-bonded oxygen atoms that are not shared are completed with acidic hydrogen atoms. The general formula of a phosphoric acid is H
, where n is the number of phosphorus atoms and x is the number of fundamental cycles in the molecule's structure, between 0 and (n+2)/2.

Laundry detergent Type of detergent used for cleaning laundry

Laundry detergent is a type of detergent used for cleaning dirty laundry (clothes). Laundry detergent is manufactured in powder and liquid form.

Sodium monofluorophosphate Chemical compound

Sodium monofluorophosphate, commonly abbreviated SMFP, is an inorganic compound with the chemical formula Na2PO3F. Typical for a salt, MFP is odourless, colourless, and water-soluble. This salt is an ingredient in some toothpastes.

Sugar soap, as typically found in Commonwealth countries, is a cleaning material of variable composition sold for use on surfaces affected by greasy or tarry deposits which are not easily removed with routine domestic cleaning materials. Its name arises from the fact that, when in dry powder form, it resembles table sugar.

Sodium hypophosphite Chemical compound

Sodium hypophosphite (NaPO2H2, also known as sodium phosphinate) is the sodium salt of hypophosphorous acid and is often encountered as the monohydrate, NaPO2H2·H2O. It is a solid at room temperature, appearing as odorless white crystals. It is soluble in water, and easily absorbs moisture from the air.

Disodium pyrophosphate Chemical compound

Disodium pyrophosphate or sodium acid pyrophosphate (SAPP) is an inorganic compound consisting of sodium cations and pyrophosphate anion. It is a white, water-soluble solid that serves as a buffering and chelating agent, with many applications in the food industry. When crystallized from water, it forms a hexahydrate, but it dehydrates above room temperature. Pyrophosphate is a polyvalent anion with a high affinity for polyvalent cations, e.g. Ca2+.

Disodium phosphate Chemical compound

Disodium phosphate (DSP), or disodium hydrogen phosphate, or sodium phosphate dibasic, is the inorganic compound with the formula Na2HPO4. It is one of several sodium phosphates. The salt is known in anhydrous form as well as forms with 2, 7, 8, and 12 hydrates. All are water-soluble white powders; the anhydrous salt being hygroscopic.

Sodium arsenate Chemical compound

Sodium arsenate is the inorganic compound with the formula Na3AsO4. Related salts are also called sodium arsenate, including Na2HAsO4 (disodium hydrogen arsenate) and NaH2AsO4 (sodium dihydrogen arsenate). The trisodium salt is a white or colourless solid that is highly toxic. It is usually handled as the dodecahydrate Na3AsO4.12H2O.

Sodium sesquicarbonate Chemical compound

Sodium sesquicarbonate (systematic name: trisodium hydrogendicarbonate) Na3H(CO3)2 is a double salt of sodium bicarbonate and sodium carbonate (NaHCO3 · Na2CO3), and has a needle-like crystal structure. However, the term is also applied to an equimolar mixture of those two salts, with whatever water of hydration the sodium carbonate includes, supplied as a powder.

Cleaning agent Substance used to remove dirt or other contaminants

Cleaning agents or hard-surface cleaners are substances used to remove dirt, including dust, stains, bad smells, and clutter on surfaces. Purposes of cleaning agents include health, beauty, removing offensive odor, and avoiding the spread of dirt and contaminants to oneself and others. Some cleaning agents can kill bacteria and clean at the same time. Others, called degreasers, contain organic solvents to help dissolve oils and fats.

Monohydrogen phosphate Chemical compound

Monohydrogen phosphate is the inorganic ion with the formula [HPO4]2-. Its formula can also be written as [PO3(OH)]2-, which shows the presence of a O-H bond. Together with dihydrogen phosphate, monohydrogen phosphate occurs widely in natural systems. Their salts are used in fertilizers and in cooking. Most monohydrogenphosphate salts are colorless, water soluble, and nontoxic.


  1. Merck Index , 12th Edition, 8808.
  2. Eagleson, Mary, ed. (1994). Concise Encyclopedia Chemistry . Walter de Gruyter. p. 1000. ISBN   978-3-11-011451-5 . Retrieved 25 May 2014.
  3. 1 2 3 4 5 6 "Sodium phosphate".
  4. 1 2 3 4 5 6 7 8 "Sodium phosphate dodecahydrate".
  5. "Archived copy" (PDF). Archived from the original (PDF) on 14 March 2016. Retrieved 25 May 2014.{{cite web}}: CS1 maint: archived copy as title (link)
  6. Sigma-Aldrich Co., Sodium phosphate. Retrieved on 2014-05-25.
  7. 1 2 Klaus Schrödter, Gerhard Bettermann, Thomas Staffel, Friedrich Wahl, Thomas Klein, Thomas Hofmann "Phosphoric Acid and Phosphates" in Ullmann’s Encyclopedia of Industrial Chemistry 2008, Wiley-VCH, Weinheim. doi : 10.1002/14356007.a19_465.pub3
  8. Dishes Still Dirty? Blame Phosphate-Free Detergent, National Public Radio, 15 December 2010
  9. "TSP ... Cleaning for the Big Dogs". Home Repair and Do It Yourself Tips and Articles from the Natural Handyman. Natural Handyman.
  10. Alonzy, Jerry. "Painting Preparation Q&A".
  11. Current EU approved additives and their E Numbers, Food Standards Agency, 26 November 2010
  12. 21CFR182.1778, Code of Federal Regulations
  13. 21CFR182.1778, Electronic Code of Federal Regulations
  14. Folland JP, et al. (2008). "Sodium phosphate loading improves laboratory cycling time-trial performance in trained cyclists". Journal of Science and Medicine in Sport. 11 (5): 464–468. doi:10.1016/j.jsams.2007.04.004. PMID   17569583.
  15. MSDS Archived 26 September 2010 at the Wayback Machine for Dap TSP cleaner