View All Products. Oral Care. The Backstory. Our Mission. Stewardship Model. Our Ingredients. Caring for the Planet. Recyclable Tube. Giving for Goodness. Our Passion is Natural. CA English. CA French. Sodium hydroxide NaOH is a white, waxy, opaque, odorless crystal consisting of sodium ions and hydroxide ions.
It is also known as lye or caustic soda and used in many industries, for pH adjustment, to purify drinking water, in household cleaners, and in soap-making. It is a highly versatile ingredient available in a wide range of grades and concentrations.
At its highest levels it is very caustic and can be used as a drain cleaner, but at dilute levels it is safe for handling and food preparation. When dissolved the hydroxide portion of the compound reacts with acids to form water. The pH is adjusted becomes more basic as some of the acid is eliminated. It is also a key ingredient to preparing many special food items.
Hominy is the preparation of dried corn kernels reconstituted by soaking them in a lye solution and pretzels owe their unique crust to being dipped in a lye solution before baking. The process was remarkable in itself, because it took a substance that wouldn't dissolve in water and made it soluble - but more so with the presumably again accidental discovery that this new product helped get things clean.
At the chemical level, in its simplest form without all the smells and subtleties, a soap is a salt of a fatty acid. Oils and fats contain mixtures of fatty acids, bonded together with the molecule glycerol to form a triglyceride.
The sodium hydroxide breaks up the triglyceride and converts the acids into sodium salts, producing the likes of sodium tallowate and sodium palmitate.
These salts act as surfactants, substances that reduce the surface tension in liquids. They form tiny balls around particles of grease, stopping the grease from being hydrophobic and allowing it to dissolve and be carried away by water. Modern soap making processes, though still based on a combination of a strong alkali like sodium hydroxide and oils or fats, are unlikely to stick with a straight sodium hydroxide and fat mix, as the soap produced is quite harsh.
Any sodium hydroxide left over can have a catastrophic effect, as it dissolves oils and fats in skin and flesh and leaves deep burns. At the extreme, sodium hydroxide will dissolve flesh entirely, and has been used to dispose of road kill and murder victims. Practically all the early soaps often called 'lye soap' were rough and left the skin red. Rather unnervingly, the destructive capability of sodium hydroxide is now used in various industrial food processes, from removing fruit skin to producing ice-cream.
You are also likely to find sodium hydroxide at work in paper mills. When paper is made from wood pulp, it starts with a mix of the substances lignin and cellulose, bonded together.
The sodium hydroxide breaks down the bonds, allowing the separation of the cellulose that will be used to form the paper. It can also be used to bleach the wood pulp to produce a white result.
If we look back into the origins of the word 'lye' the oldest name for sodium hydroxide, it comes from an old English word meaning 'wash stuff', and 'lye' was used as a term for strong soap from the 13th century onwards.
It's a rare example of putting a lye to good use. So, in the chemical industry, a lye can prove quite useful. That was Brian Clegg, with the soapy-clean chemistry of sodium hydroxide. Now, next week, a puff of paralysis. Tetrodotoxin, abbreviated to TTX, is obtained from the fugu fish, also known as the pufferfish, because when it is threatened it inflates its body to several times normal size. Symptoms start within a few minutes of ingesting it; they begin with tingling or numbness of the lips and tongue.
It spreads to other parts of the face, then more and more nerves and muscles are paralysed; the victim, who may remain fully conscious, becomes unable to move until they die of asphyxiation. And to find out just how the toxin has this effect, as well as how the pufferfish is safely served as a japanese delicacy, join Simon Cotton in next week's Chemistry in its element.
Until then, thank you for listening. I'm Meera Senthilingam. A DNA researcher tells the story of how humans have shaped the evolution of living things on Earth. Site powered by Webvision Cloud. Skip to main content Skip to navigation. Related audio. Book club — Deep Sniff by Adam Zmith. Book club — Lessons from Plants by Beronda Montgomery. Sodium hydroxide. Brian Clegg proves how a lye can be useful in the chemical industry.
Meera Senthilingam This week, some chemical lies. Here's Brian Clegg: Brian Clegg Some chemical compounds are simply known by their formulaic name - carbon dioxide, for example. Topics Chemistry in its Element: Compounds Podcasts. Latest audio.
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