Trisodium phosphate

Trisodium phosphate[1]
IUPAC name Trisodium phosphate
Other names Sodium phosphate tribasic
Identifiers
CAS number	7601-54-9 Y,  10101-89-0 (dodecahydrate)
PubChem	24243
ChemSpider	22665 Y
UNII	J9O85FKF29 Y
EC number	231-509-8
KEGG	D09000 Y
ChEBI	CHEBI:37583 Y
ChEMBL	CHEMBL363100 Y
RTECS number	TC9575000
ATC code	A06AD17,A06AG01 B05XA09 V10XX01 (32P)
Jmol-3D images	{{#if:[O-]P(=O)([O-])[O-].[Na+].[Na+].[Na+]|Image 1
SMILES [O-]P(=O)([O-])[O-].[Na+].[Na+].[Na+]
InChI InChI=1S/3Na.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3*+1;/p-3 Y Key: RYFMWSXOAZQYPI-UHFFFAOYSA-K Y InChI=1/3Na.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3*+1;/p-3 Key: RYFMWSXOAZQYPI-DFZHHIFOAM
Properties
Molecular formula	Na3PO4
Molar mass	163.94 g/mol
Density	1.620 g/cm3 (dodecahydrate)
Melting point	73.5 °C decomp. (dodecahydrate)
Solubility in water	1.5 g/100 mL (0 °C) 8.8 g/100 mL (25 °C)
Basicity (pKb)	2.23
Structure
Crystal structure	Trigonal
Hazards
MSDS	ICSC 1178
EU Index	Not listed
NFPA 704	0 2 1
Flash point	Non-flammable
Related compounds
Other cations	Tripotassium phosphate Triammonium phosphate Trimagnesium phosphate
Related compounds	Monosodium phosphate Disodium phosphate
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Trisodium phosphate (TSP) is the inorganic compound with the 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.^[2]

The item of commerce is often partially hydrated and may range from anhydrous Na₃PO₄, to the dodecahydrate, Na₃PO₄·12H₂O. Most often found in white powder form, it can also be called trisodium orthophosphate or simply sodium phosphate. Trisodium phosphate was at one time extensively used in formulations for a wide variety of consumer grade soaps and detergents, but ecological problems have largely ended that practice, at least in the western world. Substitutes are not as effective.^[3]

Production

It 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

Uses

Cleaning

The major use for trisodium phosphate is in cleaning agents. The pH of a 1% solution is 12, 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 during the late 1960s its use has diminished owing to government regulations (see below).

TSP is commonly used after cleaning with mineral spirits in order to remove hydrocarbon residues.^{[citation needed]} TSP may be used with household chlorine bleach in the same solution without hazardous reactions.^[4] This mixture is particularly good for removing mildew, but is ineffective at permanently removing mold.

Although it is still the active ingredient in some toilet bowl cleaning tablets, TSP is generally not good for cleaning bathrooms, because it can stain metal and can damage grout.^[5]

Chlorinated trisodium phosphate

With the formula Na₃PO4^.1/4NaOCl^.11H₂O, 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.^[2]

Flux

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.^[6]

Food additive

Sodium phosphates (monosodium phosphate, disodium phosphate, and trisodium phosphate) are approved as a food additive in the EU, E339.^[7]

Exercise performance enhancement

Trisodium phosphate has gained a following as a nutritional supplement that can improve certain parameters of exercise performance.^[8] 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.

Regulation

In the western world, phosphate usage has declined owing to ecological problems with the damage to lakes and rivers through eutrophication.^[9]

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.^[10]

See also

Sodium phosphates

References

External links

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