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Trisodium phosphate

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Title: Trisodium phosphate  
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Subject: Sodium hypophosphite, Laxatives, YM-31636, Movicol, Sodium tartrate
Collection: Cleaning Product Components, Edible Thickening Agents, Food Additives, Phosphates, Photographic Chemicals, Sodium Compounds
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Trisodium phosphate

Trisodium phosphate[1]
Trisodium phosphate
IUPAC name
Trisodium phosphate
Other names
Sodium phosphate tribasic
(dodecahydrate) N
ATC code A06
A06 B05
V10 (32P)
ChemSpider  Y
EC number 231-509-8
Jmol-3D images Image
RTECS number TC9575000
Molar mass 163.94 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)
73.4 °C (164.1 °F; 346.5 K)
Boiling point 100 °C (212 °F; 373 K) (dodecahydrate) decomposes[4]
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)
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]
Safety data sheet ICSC 1178
GHS pictograms The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[6]
GHS signal word Danger
H315, H318, H335[6]
P261, P280, P305+351+338[6]
Irritant Xi
R-phrases R36/37/38
S-phrases S26
NFPA 704
Flash point Non-flammable
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).
 N  (: Y/N?)

Trisodium phosphate (TSP) is the chemical formula Na3PO4. It is a white, granular or crystalline solid, highly soluble in water producing an alkaline solution. TSPs are used as cleaning agent, 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.


  • Production 1
  • Uses 2
    • Cleaning 2.1
    • Chlorinated trisodium phosphate 2.2
    • Flux 2.3
    • Painting enhancement 2.4
    • Food additive 2.5
    • Exercise performance enhancement 2.6
  • Regulation 3
    • TSP Substitutes 3.1
  • See also 4
  • References 5
  • External links 6


Trisodium phosphate is produced by neutralization of phosphoric acid using sodium hydroxides, often with sodium carbonate. Carbonate can only produce disodium phosphate:

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] Substitutes are generally not as effective.[9]

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

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.[10]

Chlorinated trisodium phosphate

With the formula Na3PO4.¼ NaOCl.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.[11]

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 antioxidant agents and have the collective E number E339.[12] The United States Food and Drug Administration lists sodium phosphates as "generally recognized as safe."[13][14]

Exercise performance enhancement

Trisodium phosphate has gained a following as a nutritional supplement that can improve certain parameters of exercise performance.[15] 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.

TSP Substitutes

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 substitute, containing soda ash and zeolites, are promoted as a direct substitute. However, sodium carbonate is not as strongly basic as trisodium phosphate, making it less effective in demanding applications. Zeolites are added to laundry detergents as bulking agents that rapidly break down in water and are essentially nonpolluting. Cleaning products labeled as TSP may contain other ingredients, with perhaps less than 50% trisodium phosphate.[16]

See also


  1. ^ Merck Index, 12th Edition, 8808.
  2. ^ Eagleson, Mary, ed. (1994). [Google Books Concise Encyclopedia Chemistry] . Walter de Gruyter. p. 1000.  
  3. ^ a b c d e f
  4. ^ a b c d e f g h
  5. ^
  6. ^ a b c Sigma-Aldrich Co., Sodium phosphate. Retrieved on 2014-05-25.
  7. ^ a b 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, December 15, 2010
  9. ^ Hotton, Peter (26 August 2010). "Handyman on Call". The Boston Globe. 
  10. ^ "TSP ... Cleaning for the Big Dogs". Home Repair and Do It Yourself Tips and Articles from the Natural Handyman. Natural Handyman. 
  11. ^ Alonzy, Jerry. "Painting Preparation Q&A". 
  12. ^ Current EU approved additives and their E Numbers, Food Standards Agency, 26 November 2010
  13. ^ 21CFR182.1778, Code of Federal Regulations
  14. ^ 21CFR182.1778, Electronic Code of Federal Regulations
  15. ^ 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.  
  16. ^ MSDS for Dap TSP cleaner

External links

  • Safety data from IPCS INCHEM
  • International Chemical Safety Card 1178
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