Create a 5 pages page paper that discusses acids and bases. A correct definition of acids and bases is important to our daily applications: the human bloodstream, cleaning materials, environment and industry.
Just like other chemical theories, acids and bases have undergone many changes in the recent past. The changes implemented have been done to ensure a more general theory. The three main theories that are applicable to the science field are:
In 1987, the first theory describing bases and acids was proposed by a Swedish chemist Svante Arrhenius (Ebbin and Gammon 624). His definition of acids and bases was based on the effects these substances had on the water. An acid was defined as a substance, which when dissolved in water, increases the concentration of hydronium ion, H3O+ (Ebbin and Gammon 625). He defined a base as a substance, which when dissolved in water, increases the concentration of hydroxide ion, OH-. Frequently chemists use hydrogen ion, H+(aq) for H3O+. Hydrogen ions are sometimes referred to as protons due to an absence of electrons in their valence shell.
Arrhenius theory was limited to substances, which could produce hydrogen or hydroxide ions in water and therefore could not explain why acids and bases, which were not in an aqueous state, did not produce hydrogen and hydroxide ions (Silberg 592). An example of such a substance is ammonia.
Danish chemist Johannes N. Bronsted and British chemist Thomas M. Lowry proposed an extension to Arrhenius definition of an acid and a base in 1923. According to them, a reaction between a base and an acid involves the transfer of protons from one species to the other. They defined an acid as a species, which donates a proton (H+) and a base a species that accepts a proton (Silberg 600). Therefore, an acid must contain H in its formula while a base must contain a lone pair of electrons, which binds with proton example is ammonia.
In the forward reaction, .H3O+ is the acid because it donates H+ to NH3 while NH3 is the base as it receives a proton from H3O+ in this proton-transfer reaction.