Sodium Hydroxide
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40 free Sodium Hydroxide trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Sodium hydroxide is one of the most useful chemicals most people never think about. Under the names lye and caustic soda it unclogs drains, turns fat into soap and gives several famous foods their look and texture, yet a careless splash can cause a serious burn. This quiz turns the best sodium hydroxide fun facts into multiple-choice questions: how the chemical is made and what comes out alongside it, the scientists and soap makers behind its story, what it does to metals and fabrics, and the surprising dishes that could not exist without it. Every answer comes with a short explanation. It suits chemistry students revising acids and bases, teachers who want a lively lesson starter, and anyone who enjoys a science fact that makes dinner guests look twice at the bread basket.
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Q 01Which Nordic Christmas dish of dried cod is soaked in lye, such as sodium hydroxide, to give a jelly-like texture?
Lutefisk
Lutefisk literally means lye fish, and the cured cod is so caustic that it needs several more days in fresh cold water before anyone can eat it.
Q 02Which German bakery classic gets its glossy brown crust from a dip in sodium hydroxide solution before baking?
Pretzel
Pretzel dough gets its dark skin and flavor from the lye dip, which drives Maillard browning as it bakes, and German bakers treat rolls and croissants the same way.
Q 03In which Brad Pitt film does a soap maker pour lye on another man's hand to cause a chemical burn?
Fight Club
Fight Club has Tyler Durden kiss the narrator's hand before pouring on the lye, and the cast took soapmaking lessons to prepare for their roles.
Q 04Which bitter Mediterranean fruit is often soaked in sodium hydroxide so that curing takes days instead of months?
Olives
Olives straight from the tree are too bitter to eat because of a compound called oleuropein, and lye strips it out in a few days where other cures take months.
Q 05Which American household product, invented in 1923, combines sodium hydroxide crystals with shards of aluminum?
Drano
Drano fizzes in a wet pipe because the metal reacts with the lye, and the bubbling stirs the mix while the lye turns greasy clogs into soap.
Q 06Which flammable gas builds up when sodium hydroxide touches aluminum, as happened inside a British road tanker in 1986?
Hydrogen
Hydrogen is released as the metal dissolves, and in 1986 it pressurized a tanker that had been loaded with sodium hydroxide solution by mistake.
Q 07Which Chinese preserved delicacy, set into dark jelly by sodium hydroxide, is wrongly said to be soaked in horse urine?
Century egg
Century egg curing works by slowly raising the pH inside the shell to as high as 12, and the horse rumor may owe something to the smell of ammonia.
Q 08Whose autobiography describes getting his first conk, a hairstyle made by combing burning lye through the hair?
Malcolm X
Malcolm X later condemned the conk as degrading, and the homemade lye gel, often mixed with potatoes, could burn the scalp badly if it stayed on too long.
Q 09Soaking the dried kernels of which grain in lye produces hominy, the starting point for Southern grits?
Corn
Corn soaked in lye sheds its tough hulls and softens, and the treatment also frees the vitamin niacin so the body can absorb it.
Q 10Food factories dip fruits and vegetables in sodium hydroxide solution to carry out which step before canning?
Peeling
Peeling by chemical bath is one of several food jobs for sodium hydroxide, which also helps process cocoa, color caramel and thicken ice cream.
Q 11Which English chemist first isolated sodium metal in 1807 by passing an electric current through molten caustic soda?
Humphry Davy
Humphry Davy went on to isolate calcium, barium and magnesium the following year, using electricity to pull apart compounds nobody had managed to split.
Q 12Factories that make sodium hydroxide by electrolysis also turn out which gas, widely used to disinfect drinking water?
Chlorine
Chlorine and sodium hydroxide leave the cell in fixed proportions, so producers have to find buyers for both products at the same time.
Q 13Sodium hydroxide neutralizes which acid, also found in the human stomach, to leave only table salt and water?
Hydrochloric
Q 21The Bayer process cooks which ore in hot sodium hydroxide solution to extract the raw material for aluminum?
Bauxite
Bauxite dissolves only in part, so the alumina goes into solution while the iron oxides stay behind as a caustic waste known as red mud.
Q 22In 1844 John Mercer found that sodium hydroxide makes which natural fiber stronger and far easier to dye?
Cotton
Cotton treated this way is still called mercerized, though the silky shine sold today came decades later, when Horace Lowe added tension.
Q 23Which fabric, long sold as artificial silk, is made by treating wood pulp with sodium hydroxide?
Rayon
Rayon starts as pulp steeped in caustic soda, which is later dissolved into a syrup called viscose and forced through a spinneret to make filaments.
Hydrochloric acid and sodium hydroxide cancel each other so neatly that teachers use the pair to show students the two ends of the pH scale.
Q 14Which color does the indicator phenolphthalein turn when a few drops of sodium hydroxide make a solution basic?
Pink
Pink appears once the solution turns basic, above a pH of about 8, yet in very strong sodium hydroxide the color slowly fades away again.
Q 15The Na in sodium hydroxide's formula comes from natron, a natural mineral salt harvested in which ancient land?
Egypt
Egypt's natron inspired the Neo-Latin name natrium, which the Swedish chemist Berzelius shortened to Na in his 1814 system of atomic symbols.
Q 16Dilute sodium hydroxide gives fingers which telltale feeling as it converts the skin's natural oils into soap?
Slippery
Slippery fingers mean the chemical is already reacting with the skin, a soap-forming process that chemists call saponification.
Q 17Hard bar soap is made with sodium hydroxide, but liquid soaps usually rely on the hydroxide of which other metal?
Potassium
Potassium hydroxide gives softer soaps that dissolve more easily, while sodium hydroxide is the cheaper of the two and less of it is needed.
Q 18Solid sodium hydroxide must be kept in airtight containers because it absorbs moisture and which gas from the air?
Carbon dioxide
Carbon dioxide and moisture both spoil the chemical, and a pellet left in open air soaks up so much water vapor that it dissolves itself.
Q 19Which common laboratory material is slowly attacked by sodium hydroxide, causing joints and stopcocks to seize up?
Glass
Glass slowly dissolves into soluble silicates, so hot sodium hydroxide leaves flasks frosted and the chemical is usually stored in plastic or steel.
Q 20One of the biggest industrial uses of sodium hydroxide is turning wood into which everyday material?
Paper
Paper mills cook wood chips in sodium hydroxide to dissolve lignin, the natural glue that holds the cellulose fibers together.
Q 24Sodium hydroxide acts as the catalyst when vegetable oil and methanol are turned into which alternative fuel?
Biodiesel
Biodiesel makers must keep the mix dry, because sodium hydroxide combined with water would turn the oil into soap instead of fuel.
Q 25Sodium hydroxide is the grease-dissolving ingredient in many spray cleaners made for which kitchen appliance?
Oven
Oven cleaners rely on lye to break baked-on grease into residues that wash off, the same chemistry that drain openers use on clogs.
Q 26Water utilities add sodium hydroxide to raise pH so that less of which toxic metal dissolves from old pipes?
Lead
Lead and copper dissolve less readily once the pH goes up, so the same chemical that unclogs drains also helps keep tap water safe.
Q 27Stirring sodium hydroxide pellets into water has which dramatic effect on the solution, a known hazard for soap makers?
It heats up
It heats up so sharply that adding the pellets too quickly can make the mixture boil or erupt, a kind of reaction chemists call exothermic.
Q 28A recipe for sodium hydroxide appears in a late-1200s Arab book on soap making compiled by a king of which country?
Yemen
Yemen's King al-Muzaffar Yusuf compiled the book, whose recipe ran water again and again through plant ash and quicklime to draw out the caustic liquid.
Q 29Which French chemist patented a 1791 method for making soda ash, the raw material for early caustic soda?
Nicolas Leblanc
Nicolas Leblanc was never paid the prize money he had earned, and revolutionaries later seized his factory and published his trade secrets.
Q 30The Castner–Kellner process made sodium hydroxide in cells built around an electrode of which toxic metal?
Mercury
Mercury from one such plant in Ontario, Canada, poisoned river fish and the people who ate them, a reason mercury cells have largely given way to membrane cells.