bronsted-lowery concept of acids and bases
The Bronsted-Lowery concept of acids and bases is that acid-base reactions can be seen as proton-transfer reactions. This results in acids and bases being able to be defined in terms of this proton (H+) transfer. According to the Bronsted-Lowery concept, acids donate a proton in a proton-transfer reactions. Bases accept the proton in a proton-transfer equation. As an example, lets look at the reaction of hydrochloric acid with ammonia. When we write it as an ionic equation we get:
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reaction of hydrochloric acid with ammonia
which reduces to:
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reduced reaction of hydrochloric acid with ammonia
because there is a Cl-(aq), on each side. We now have the net ionic equation after we cancel out the "spectator ions"(Cl-).
What happens in this reaction in aqueous solution is that a proton is transferred from H3O+ to NH3. This results in H3O+ losing a (H+), resulting in H2O. The NH3 gains the transferred proton, resulting in NH4+. We call H3O+ the proton donor, or acid. We call NH3 the proton acceptor, or base
The Bronsted-Lowery concept defines something as either an acid or base depending on its function in the acid-base (proton transfer) reaction. Some things can act as either an acid or a base. These are called amphiprotic species, they can either lose or gain a proton, depending on the other reactant. An example of an amphiprotic species would be:
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example of an amphiprotic species
In the presence of OH-, it acts as an acid. In the presence of HF it acts as a base. Water is also amphiprotic, as are most anions with ionizable hydrogens and certain solvents. Water as an amphiprotic species is very important to the acid-base reactions.
In the Bronsted-Lowery concept we have found that:
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