Base Definition in Chemistry

Base Definition in Chemistry In chemistry, a base is a chemical species that donates electrons, accepts protons, or releases hydroxide (OHs of bases include alkali metal hydroxides, alkaline earth metal hydroxides, and soap. Key Takeaways: Base Definition A base is a substance that reacts with an acid in an acid-base reaction.The mechanism through which a base works has been argued throughout history. Generally, a base either accepts a proton, releases a hydroxide anion when dissolved in water, or donates an electron.Examples of bases include hydroxides and soap. Word Origin The word base came into use in 1717 by French chemist Louis Là ©mery. Là ©mery used the word as a synonym for Paracelsus alchemical concept of a matrix in alchemy. Paracelsus proposed natural salts grew as a result of a universal acid mixing with a matrix. While Là ©mery may have used the word base first, its modern usage is generally attributed to French chemist Guillaumes of Rouelles bases included alkalis, metals, oils, or absorbent earth. In the 18th century, salts were solid crystals, while acids were liquids. So, it made sense to early chemists that the material that neutralized the acid somehow destroyed its spirit and allowed it to take solid form. Properties of a Base A base displays several characteristic properties: Aqueous base solution or molten bases dissociate into ions and conduct electricity.Strong bases and concentrated bases are caustic. They react vigorously with acids and organic matter.Bases react in predictable ways with pH indicators. A base turns litmus paper blue, methyl orange yellow, and phenolphthalein pink. Bromothymol blue remains blue in the presence of a base.A basic solution has a pH greater than 7.Bases have a bitter flavor. (Dont taste them!) Types of Bases Bases may be categorized according to their degree of dissociation in water and reactivity. A strong base completely dissociates into its ions in water or is a compound that can remove a proton (H) from a very weak acid. Examples of strong bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH).A weak base incompletely dissociates in water. Its aqueous solution includes both the weak base and its conjugate acid.A superbase is even better at deprotonation than a strong base. These bases have very weak conjugate acids. Such bases are formed by mixing an alkali metal with its conjugate acid. A superbase cannot remain in aqueous solution because it is a stronger base than the hydroxide ion. An example of a superbase in sodium hydride (NaH). The strongest superbase is the orthos include silicon dioxide (SiO2) and NaOH mounted on alumina. Solid bases may be used in anion exchange resins or for reactions with gaseous acids. Reaction Between an Acid and a Base An acid and a base react with each other in a neutralization reaction. In neutralization, an aqueous acid and aqueous base produce an aqueous solution of salt and water. If the salt is saturated or insoluble, then it may precipitate out of the solution. While it may seem like acids and bases are opposites, some species can act as either an acid or a base. In fact, some strong acids can act as bases. Sources Jensen, William B. (2006). The origin of the term base. The Journal of Chemical Education. 83 (8): 1130. doi:10.1021/ed083p1130Johll, Matthew E. (2009). Investigating chemistry: a forensic science perspective (2nd ed.). New York: W. H. Freeman and Co. ISBN 1429209895.Whitten, Kenneth W.; Peck, Larry; Davis, Raymond E.; Lockwood, Lisa; Stanley, George G. (2009). Chemistry (9th ed.). ISBN 0-495-39163-8.Zumdahl, Steven; DeCoste, Donald (2013).  Chemical Principles  (7th ed.). Mary Finch.