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Trisodium phosphate

physical science Maturity 5-7 Next article →

Trisodium phosphate is a very useful white solid. It often looks like small grains or a fine powder. This substance is an inorganic compound with the formula Na3PO4. It dissolves very easily in water. When it dissolves, it creates an alkaline solution. This means the liquid is very basic. A 1% solution has a pH of 12. This high number shows how strong it is.

Making this substance is a two-step way of working. First, workers mix phosphoric acid with sodium carbonate. This step produces something called disodium hydrogen phosphate. Next, they react that substance with sodium hydroxide. This final step creates trisodium phosphate and water. The finished product can be anhydrous or a dodecahydrate. It is often sold as a white powder.

People have used this powder for many years. In the mid-20th century, it was in many soaps. It was a very popular base for cleaning products. This was because it was cheap to make. It was also very versatile for many jobs. Today, its use has gone down in the United States. Many parts of the world use it less too.

This powder has many different jobs. It can turn grease and oils into soap. This helps clean everything from laundry to driveways. It also helps new paint stick to old walls. In plumbing, it acts as a flux. A flux is a substance that helps join metal. It dissolves copper oxides during the brazing process. It is also used as a food additive. In the EU, it has the E number E339.

We must be careful with how we use it. If it gets into lakes, it causes eutrophication. This is a process that can harm water systems. Because of this, many people use substitutes now. Some substitutes use sodium carbonate or zeolites. Zeolites are made from clay and help soften water. They are much better for the environment. They do not cause the same damage to rivers.

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