Effect of EN vs Bond Length on Acid Strength [ENDORSED]

[Carly Yoon]

For Week 10 Achieve #11, I understand that Cl is more EN than I, but in class, Lavelle said that shorter bonds cause weaker acids - and Cl has the shortest bond…?

[Ethan Cheng 2k]

You can't compare bond lengths using atomic radius in this question because Cl and the other halides are not bonded to the H in the acid. For example, HClO looks like Cl-O-H. You have to compare the EN of the different halides to determine the halide that has the greatest pull on electrons, which determines which acid has the weakest O-H bond and is therefore the strongest acid.

[Sidharth Paparaju 3B]

When comparing binary acids HA where A is in the same group, we look for the weaker bond via length. So, HI and HCl have the A in the same group, and I has the greater radius so its bond would be weaker, hence its the stronger acid.

You would use EN when comparing binary acids of the same period or with oxoacids.

[Aida Fraser 2I]

whats a binary vs oxoacid?