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There are numerous possible ways to define and acid and a base. One common
way is the Bronsted-Lowery acid base model:
- An acid is a proton (H+) donor
- A base is a proton (H+) acceptor
In an acid-base
reaction, one or more protons are transferred from the acid molecule to the base
molecule. A general form for the reaction is shown below:
- HA(aq) + B-(aq) - > A-(aq) +
HB(aq)
In the
above reaction
- HA is the acid
- B- is the base
The species produced when a proton
leaves an acid is known as the conjugate base of that acid. In a similar
fashion, the species that is formed when the base adds a proton is the
conjugate acid of that base. For the above reaction
- A- is the conjugate base of the acid HA
- HB is the conjugate acid of the base B-
Example: For the reaction below, identify the acid, base, and
conjugate acids and bases
- HF(aq) + OH-(aq) -> F-(aq) +
H2O(l)
Solution: HF is the acid, OH- is the base,
F- is the conjugate base of the acid HF, and water is the conjugate
acid of the base OH-. |