Science, Tech, Math › Science Strong Base Definition and Examples Chemistry Glossary Definition of Strong Base Share Flipboard Email Print Sodium hydroxide is an example of a strong base. Laguna Design / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated November 04, 2019 A strong base is a base that is completely dissociated in an aqueous solution. These compounds ionize in water to yield one or more hydroxide ion (OH-) per molecule of base. In contrast, a weak base only partially dissociates into its ions in water. Ammonia is a good example of a weak base. Strong bases react with strong acids to form stable compounds. Examples of Strong Bases Fortunately, there aren't very many strong bases. They are hydroxides of the alkali metals and alkaline earth metals. Here is a table of the strong bases and a look at the ions they form: Base Formula Ions sodium hydroxide NaOH Na+(aq) + OH-(aq) potassium hydroxide KOH K+(aq) + OH-(aq) lithium hydroxide LiOH Li+(aq) + OH-(aq) rubidium hydroxide RbOH Rb+(aq) + OH-(aq) cesium hydroxide CsOH Cs+(aq) + OH-(aq) calcium hydroxide Ca(OH)2 Ca2+(aq) + 2OH-(aq) barium hydroxide Ba(OH)2 Ba2+(aq) + 2OH-(aq) strontium hydroxide Sr(OH)2 Sr2+(aq) + 2OH-(aq) Note that while calcium hydroxide, barium hydroxide, and strontium hydroxide are strong bases, they are not very soluble in water. The small amount of compound that dissolves dissociates into ions, but most of the compound remains a solid. The conjugate bases of very weak acids (pKa greater than 13) are strong bases. Superbases The Group 1 (alkali metal) salts of amides, carbanions, and hydroxides are called superbases. These compounds cannot be kept in aqueous solutions because they are stronger bases than the hydroxide ion. They deprotonate water. What Are the Strong Bases? What Determines the Strength of an Acid or Base? What Is a Base in Chemistry? Learn The Chemistry Behind Salt Formation Definitions of pH, pKa, Ka, pKb, and Kb What Is a Net Ionic Equation? Review Your Chemistry Concepts What Is a Weak Acid? Common Strong and Weak Acids and Ways to Tell Them Apart Here's What an Acid Is in Chemistry Do You Know How to Use Ionic Equations in Chemistry? What Is an Acid-Base Indicator? Difference Between Strong and Weak Electrolytes Why Hydrofluoric Acid Is a Weak Acid How Dissociation Reactions Work in Chemistry Understand the Relationship Between pH and pKa What Is the Reactivity Series in Chemistry?