# How do you determine conjugate acids and bases?

Jun 23, 2016

The conjugate base of any species is the original species LESS a proton, ${H}^{+}$.

#### Explanation:

And the conjugate acid of any species is the original species PL:US a proton, ${H}^{+}$. As with any chemical reaction, both MASS and CHARGE are conserved.

So let's start with water, ${H}_{2} O$. Add ${H}^{+}$ and we get hydronium ion, ${H}_{3} {O}^{+}$, formally the conjugate acid. Remove ${H}^{+}$ from water and we get $H {O}^{-}$, the conjugate base.

So now consider sulfuric acid, ${H}_{2} S {O}_{4}$. If you are following me, then its conjugate base is $H S {O}_{4}^{-}$, bisulfate. And the conjugate base of bisulfate is $S {O}_{4}^{2 -}$. What is the conjugate acid of bisulfate?

So now let's complicate matters. Ammonia is a Bronsted-Lowry base in water:

$N {H}_{3} + {H}_{2} O r i g h t \le f t h a r p \infty n s N {H}_{4}^{+} + H {O}^{-}$

And clearly, the conjugate acid of ammonia is ammonium, $N {H}_{4}^{+}$. By this process, can you tell me the conjugate base of ammonia? This does not exist in water, but does exist in liquid ammonia as the amide ion. Note that this conjugate base also has a conjugate base with a $- 2$ charge, the imide ion. Can you formulate it? And, this conjugate base, also has a conjugate base, the azide ion; its formulation? And we have reached the end of the chain.