# conjugate acid and conjugate base

#### teefRcool

##### Senior Member
10+ Year Member
can someone pleaaaaaaase explain how those work and what they mean i always miss the questions where they ask which is conj acid or base!!!
tnx

#### Notoriousjae

##### DAT Rockstar
10+ Year Member
teefRcool said:
can someone pleaaaaaaase explain how those work and what they mean i always miss the questions where they ask which is conj acid or base!!!
tnx

According to the Bronsted-Lowry theory of acids and bases, an acid is a proton donor and a base is a proton acceptor. Once, an acid has given up a proton, the remaining part can be a proton acceptor, and thus a base. In this regard, an acid and a base are closely related to one another.
H+ + Base = Conjugate_acid of Base+
Acid = H+ + Conjugate_base of Acid-
For example:
NH3 + H2O = NH4+ + OH-
HAc = H+ + Ac-
Thus, NH4+ and NH3 are a pair of conjugate acids and bases, as are HAc and Ac-.

#### tom_servo_dds

##### Senior Member
10+ Year Member
Notoriousjae said:
According to the Bronsted-Lowry theory of acids and bases, an acid is a proton donor and a base is a proton acceptor. Once, an acid has given up a proton, the remaining part can be a proton acceptor, and thus a base. In this regard, an acid and a base are closely related to one another.
H+ + Base = Conjugate_acid of Base+
Acid = H+ + Conjugate_base of Acid-
For example:
NH3 + H2O = NH4+ + OH-
HAc = H+ + Ac-
Thus, NH4+ and NH3 are a pair of conjugate acids and bases, as are HAc and Ac-.
Good explanation. Another great example is H2O. On one sense it can be considered a base if it accepts an additional H+ to become H3O+. The hydronium ion produced is then considered it's conjugate acid. If however, the H2O molecule gave up a H+ then it would be acting as an acid and the OH- produced would be considered it's conjugate base. Many such species as this exist including H2SO4 (hydrogen sulfate), H2CO3 (carbonic acid which is used in the bloodstream to buffer systems - it is this property of carbonic acid that give it such good properties as a buffer in fact).