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11.2 Brønsted-Lowry Acids and Bases

  • Page ID
    171962
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    and is limited to aqueous (that is, water) solutions. Although this is useful because water is a common solvent, it is limited to the relationship between the H ion and the OH ion. What would be useful is a general definition more applicable to other chemical reactions and, importantly, independent of HO. is any species that can donate a proton (H) to another molecule. A is any species that can accept a proton from another molecule. In short, a Brønsted-Lowry is a proton donor (PD), while a is a proton acceptor (PA). - reaction: }{H^{+}(aq)}+\underset{}{OH^{-}(aq)}\rightarrow H_{2}O\, (l)\nonumber \] species and species are marked. The proton, however, is (by definition) a proton donor (labeled PD), while the OH ion is acting as the proton acceptor (labeled PA): , and the proton acceptor is the : }{H^{+}(aq)}+\underset{BL\, }{OH^{-}(aq)}\rightarrow H_{2}O\, (l)\nonumber \] by both definitions, and OH is a by both definitions. even though it does not contain OH ions in its formula. Instead, it generates OH ions as the product of a proton-transfer reaction with HO ; NH acts like a , and HO acts like a Brønsted-Lowry : ; we say that NH hydrolyzes to make NH ions and OH ions. in water can be considered a Brønsted-Lowry - reaction. Consider the process of dissolving HCl(g) in water to make an aqueous of hydrochloric . The process can be written as follows: , while HO is the proton acceptor and a . These two examples show that HO can act as both a proton donor and a proton acceptor, depending on what other is in the chemical reaction. A that can act as a proton donor or a proton acceptor is called . Water is probably the most common we will encounter, but other substances are also . , while the OH ion, the proton acceptor, is acting as a . The reverse reaction is also a Brønsted-Lowry reaction: - reactions by the Brønsted-Lowry definition. If you consider the species in this chemical reaction, two sets of similar species exist on both sides. Within each set, the two species differ by a proton in their formulas, and one member of the set is a Brønsted-Lowry , while the other member is a . These sets are marked here: . We say that NH is the conjugate of NH, OH is the conjugate of HO, and so forth. Every Brønsted-Lowry - reaction can be labeled with two .


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