Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Sodium hydroxide
open-in-new
<p>Sodium hydroxide, also known as lye and caustic soda, is an <a href="/facts/Inorganic_compound/TfFfzxSz">inorganic compound</a> with the formula NaOH. It is a white solid <a href="/facts/Ionic_compound/jB9nMfrE">ionic compound</a> consisting of <a href="/facts/Sodium/eYuSPu2V">sodium</a> <a href="/facts/Cation/wrbwhF3z">cations</a> Na+ and <a href="/facts/Hydroxide/zW0wxpWD">hydroxide</a> <a href="/facts/Anion/wrbwhF3z">anions</a> OH−. </p><p>Sodium hydroxide is a highly <a href="/facts/Corrosive/7LXjT1XE">corrosive</a> <a href="/facts/Base_(chemistry)/M9wA7qeM">base</a> and <a href="/facts/Alkali/s6NqPGSP">alkali</a> that decomposes <a href="/facts/Lipid/TdQR87HX">lipids</a> and <a href="/facts/Protein/Jxmagu3E">proteins</a> at ambient <a href="/facts/Temperature/QyGe4gmj">temperatures</a> and may cause severe <a href="/facts/Chemical_burn/GycBJMJo">chemical burns</a>. It is highly soluble in <a href="/facts/Water/0lkXnJPK">water</a>, and readily absorbs <a href="/facts/Moisture/vubw4SpX">moisture</a> and <a href="/facts/Carbon_dioxide/xGzpppEp">carbon dioxide</a> from the <a href="/facts/Air/hQ95Jznz">air</a>. It forms a series of <a href="/facts/Hydrate/dev82l69">hydrates</a> NaOH·<i>n</i>H2O. The monohydrate NaOH·H2O crystallizes from water solutions between 12.3 and 61.8 °C. The commercially available "sodium hydroxide" is often this monohydrate, and published data may refer to it instead of the <a href="/facts/Anhydrous/A7B0fDLE">anhydrous</a> compound. </p><p>As one of the simplest hydroxides, sodium hydroxide is frequently used alongside neutral <a href="/facts/Water/0lkXnJPK">water</a> and acidic <a href="/facts/Hydrochloric_acid/HqItJlUT">hydrochloric acid</a> to demonstrate the pH scale to chemistry students. </p><p>Sodium hydroxide is used in many industries: in the making of <a href="/facts/Wood_pulp/wIlq5nWm">wood pulp</a> and <a href="/facts/Paper/FUETwwKV">paper</a>, <a href="/facts/Textile/PJrVeM5S">textiles</a>, <a href="/facts/Drinking_water/FmSJcKGG">drinking water</a>, <a href="/facts/Soap/S3nJa1oY">soaps</a> and <a href="/facts/Detergent/4FLKXR6p">detergents</a>, and as a <a href="/facts/Chemical_drain_cleaners/DvtePqwl">drain cleaner</a>. Worldwide production in 2022 was approximately 83 million tons. </p>