Problem 14−133

Acid strength according to the structure

a) By giving the value of the bond energy, it is easy to know which one will be the most acidic: The weaker the "−H" bond the stronger the acid (more dissociated).

b) This concerns the inductive effect. Once the “−H” bond is broken, the negative charge remains on the oxygen. If the neighbor (the closest atom to oxygen) is electronegative, this will help stabilize the negative charge, making the acid stronger.

c) Here, once the H⁺ disappears, there is no longer a negative charge on the nitrogen, which makes the two molecules equally stable.
However, when H⁺ is present on the nitrogen, the oxygen neighbor is an electronegative atom (HO−NH₃⁺) which attracts electrons from N. Then, the nitrogen, already less stable with additional H⁺, will become even less so. The only option is to drop his H⁺. Therefore, it will also be more acidic (or stronger) than the other ion (NH₄⁺)

d) Same as (a), the weakest bond will make the stronger acid.