chemistry

Trisodium phosphate

Trisodium phosphate is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Trisodium phosphate rather than just read about it. In short: Trisodium phosphate (TSP) is an inorganic compound with the chemical formula Na3PO4. It is a white, granular or crystalline solid, highly soluble in water, producing an alkaline solution.

Key takeaways

Trisodium phosphate belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Trisodium phosphate to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Trisodium phosphate from memory before moving on to harder problems.

Reference excerpt

Trisodium phosphate (TSP) is an inorganic compound with the chemical formula Na3PO4. 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. As an item of commerce TSP is often partially hydrated and may range from anhydrous Na3PO4 to the dodecahydrate Na3PO4·12H2O. Most often it is found in white powder form. It can also be called trisodium orthophosphate or simply sodium phosphate.

Production 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

Uses

Cleaning 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. 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. 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.

Chlorination With the formula 4Na3PO4·NaOCl·44H2O 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.

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.

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. The United States Food and Drug Administration lists sodium phosphates as generally recognized as safe.

Exercise performance enhancement Trisodium phosphate has gained a following as a nutritional supplement that can improve certain parameters of exercise performance. 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.

Regulation In the Western world, phosphate usage has declined because of damage it causes to lakes and rivers through eutrophication.

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 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. 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. Cleaning products labeled as TSP may contain other ingredients, with perhaps less than 50% trisodium phosphate.

References

External links Safety data from IPCS INCHEM International Chemical Safety Card 1178

Illustrations

Worked examples

Example 1 — a first encounter with Trisodium phosphate

Start with the simplest possible case. Write down what Trisodium phosphate claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Trisodium phosphate before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Trisodium phosphate ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Trisodium phosphate

In research: Trisodium phosphate appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Trisodium phosphate in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Trisodium phosphate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cleaning product components, E-number additives, Edible thickening agents, so understanding it makes those chapters shorter.
In everyday life: Look for Trisodium phosphate outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Trisodium phosphate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Trisodium phosphate means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Trisodium phosphate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Trisodium phosphate in simple terms?

Trisodium phosphate (TSP) is an inorganic compound with the chemical formula Na3PO4. It is a white, granular or crystalline solid, highly soluble in water, producing an alkaline solution.

Why does Trisodium phosphate matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Trisodium phosphate?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Trisodium phosphate.