There are several definitions for each of these terms depending upon how exclusive you make your definition.
Traditionally Professor Arrhenius defined these terms as follows:
Acid- a substance that produced Hydrogen ion in water solution. The hydrogen ions were hydrated as Hydronium ions.
Base- a substance that produced Hydroxide ion in water solution. These definitions were very restrictive. The limitations on these definitions were:
1. The need for water so only aqueous solutions were covered (non-aqueous solutions were excluded)
2. The need for a protic acid since hydrogen ions had to be produced
3. The need for Hydroxide bases
You can receive a short biography of Professor Arrenhius.
Professors Bronsted and Lowry defined these two terms the following:
Acid- Proton donor
Base- Proton acceptor
These definitions are not as restrictive as the first set of definitions.
1. First, there is no need for water although it can be present, it need not be. Therefore non-aqueous systems are included.
2. Secondly, bases do not have to be Hydroxide compounds.
However, one restriction still remaining is the need for a protic acid.
Professor G.N. Lewis defined these two terms in even a less restrictive manner and included even more examples:
Acid- Electron acceptor
Base- Electron donor
In this set of definitions there is no longer a need for a protic acid. In other words only electron exchange must occur.
By the way these definition sets are NOT contradictory. A Proton donor is the same as an electron acceptor. A Proton acceptor is the same as an electron donor. Also the first set of definitions are less inclusive so that all of the Arrenhius acids are found under the Bronsted definition but not all Bronsted acids will be Arrenhius acids. All Arrenhius and Bronsted acids will be under the Lewis definition but not all Lewis acids will be Bronsted or Arrenhius acids.
You may acess a short biography of Gilbert Newton Lewis here.
The properties of acids include the following:
Some common examples of acids are vinegar (5% acetic acid), citric acid (found in citrus vegetables and fruits), Muriatic Acid (Hydrochloric Acid), Carbonic Acid (found in carbonated drinks), Lactic Acid (Found in Buttermilk). The properties of bases include the following:
Some common bases include Aqueous Ammonia (Household cleaner), Detergents, Soaps, and Lye (NaOH).
R. H. Logan, Instructor of Chemistry, Dallas County Community College District, El Centro College.
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All textual content copyrighted (c) 1995 R.H. Logan, Instructor of Chemistry, DCCCD All Rights reserved
Revised: 3/31/96
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