Question

Since acids have 1 more proton (H+ - ions) than base, and the acid gives it away, doesn't that mean that they switch roles? Acid becomes base, and base becomes acid...?
Thanks for clarifying .. :)

Answer 1

Answer:

In an acid-base equilibrium, acid becomes a conjugate base and base becomes a conjugate acid.

Explanation:

Let's remember the Bronsted-Lowry theory to answer this specific question. According to the theory, acid is a proton donor, while a base is a proton acceptor.

Consider an acid in a form HA (aq) and base in a form of B (aq). Since acid is a proton donor, it will donate its hydrogen ion to the base, B. The resultant products would be $A^{-}$ (aq) and $BH^{+}$ (aq).

Remember that an acid-base reaction is an equilibrium reaction. This means we may also look at this proton transfer reaction from the product side towards the reactants. Summarizing what has been said, we may write the equilibrium as:

$HA (aq) + B (aq)$ ⇄ $BH^{+} (aq) + A^{-} (aq)$

Now acid, HA, donates a proton to become a conjugate base. The conjugate base, if we look from the reverse equation side, is actually a base, since it can accept a proton to become HA. Similarly, B accepts a proton to become a conjugate acid. Looking from the reverse reaction, it can now donate a proton, so in reality we can consider it a base.

To summarize, your logic is correct.