Science, Tech, Math › Science Strength of Acids and Bases Strong and Weak Acids & Bases Share Flipboard Email Print Lithium hydroxide is an example of a strong base. CCoil/Wikimedia Commons/CC By 3.0 Science Chemistry Basics Chemical Laws 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 July 03, 2019 Strong electrolytes are completely dissociated into ions in water. The acid or base molecule does not exist in aqueous solution, only ions. Weak electrolytes are incompletely dissociated. Here are definitions and examples of strong and weak acids and strong and weak bases. Strong Acids Strong acids completely dissociate in water, forming H+ and an anion. There are six strong acids. The others are considered to be weak acids. You should commit the strong acids to memory: HCl: hydrochloric acid HNO3: nitric acid H2SO4: sulfuric acid HBr: hydrobromic acid HI: hydroiodic acid HClO4: perchloric acid If the acid is 100 percent dissociated in solutions of 1.0 M or less, it is called strong. Sulfuric acid is considered strong only in its first dissociation step; 100 percent dissociation isn't true as solutions become more concentrated. H2SO4 → H+ + HSO4- Weak Acids A weak acid only partially dissociates in water to give H+ and the anion. Examples of weak acids include hydrofluoric acid, HF, and acetic acid, CH3COOH. Weak acids include: Molecules that contain an ionizable proton. A molecule with a formula starting with H usually is an acid. Organic acids containing one or more carboxyl group, -COOH. The H is ionizable. Anions with an ionizable proton (e.g., HSO4- → H+ + SO42-). Cations Transition metal cations Heavy metal cations with high charge NH4+ dissociates into NH3 + H+ Strong Bases Strong bases dissociate 100 percent into the cation and OH- (hydroxide ion). The hydroxides of the Group I and Group II metals usually are considered to be strong bases. LiOH: lithium hydroxide NaOH: sodium hydroxide KOH: potassium hydroxide RbOH: rubidium hydroxide CsOH: cesium hydroxide *Ca(OH)2: calcium hydroxide *Sr(OH)2: strontium hydroxide *Ba(OH)2: barium hydroxide * These bases completely dissociate in solutions of 0.01 M or less. The other bases make solutions of 1.0 M and are 100 percent dissociated at that concentration. There are other strong bases than those listed, but they are not often encountered. Weak Bases Examples of weak bases include ammonia, NH3, and diethylamine, (CH3CH2)2NH. Like weak acids, weak bases do not completely dissociate in aqueous solution. Most weak bases are anions of weak acids. Weak bases do not furnish OH- ions by dissociation. Instead, they react with water to generate OH- ions. Cite this Article Format mla apa chicago Your Citation Helmenstine, Anne Marie, Ph.D. "Strength of Acids and Bases." ThoughtCo, Aug. 26, 2020, thoughtco.com/strong-and-weak-acids-and-bases-603667. Helmenstine, Anne Marie, Ph.D. (2020, August 26). Strength of Acids and Bases. Retrieved from https://www.thoughtco.com/strong-and-weak-acids-and-bases-603667 Helmenstine, Anne Marie, Ph.D. "Strength of Acids and Bases." ThoughtCo. https://www.thoughtco.com/strong-and-weak-acids-and-bases-603667 (accessed April 18, 2021). copy citation Watch Now: What are the Differences Between Acids and Bases?