In this section we will consider the Brønsted-Lowry concept. This concept focuses on what an acid or base does.
With the Brønsted-Lowry concept we usually refer to a hydrogen ion as a proton. That is because a proton is all that is left when a hydrogen atom loses an electron to become an ion.
Brønsted and Lowry independently came up with the idea that an acid is an acid because it provides or donates a proton to something else. When an acid reacts, the proton is transferred from one chemical to another. As will be noted later, the chemical which accepts the proton is a base.
The first chemical in each of these equations is an acid because they are each giving a proton to something else.
Note that in order for an acid to act like an acid, there needs to be something for it to react with. There needs to be something to take the proton. There needs to be a base. A base is a proton acceptor. Compare this to the definition that an acid is a proton donor.
Hydroxide, ammonia, carbonate and water are all Brønsted-Lowry bases.
Be sure to note the distinction between ammonia and ammonium. NH3 is ammonia and NH4+ is ammonium. They sound very much the same and their formulas are very similar, but their chemical properties are quite different. They are different because one has one more proton than the other. Ammonia is a base and ammonium is an acid. We'll take up another aspect of their relationship when we consider conjugate pairs.
Some phenomena that are readily explained using the Brønsted-Lowry concept are acid-base reactions (explained as proton transfer reactions), conjugate pair relationships, and amphoterism.
E-mail instructor: Eden Francis
Clackamas Community College