Determining Acid Strength

[Barbara Soliman 1G]

What are general things we should be looking at when determining if one acid or base is stronger than another?

For example, I am having trouble with Focus 6C.19 c, d, and f. I thought for c and f, since Br and Ge each have a larger atomic radius, than Cl and C, respectively, they would have a weaker bond, thus making them stronger acids. For d, I thought that since H3PO4 has more than one H, it would be more willing to give off of an H. Could someone please clarify? Thanks!

[Jenny Han 3F]

When the H is bonded to the atom in question (that differs between the options), we look at the electronegativity difference to gauge the delocalization and stabilization. If that atom is not bonded to H, we look to other disparities like resonance and bond length. With all the examples you mentioned, the H is bonded to the atom in question, which means the electronegativity makes the stronger acids stronger.

[Ashley Presnell 1C]

If the atom bonded to the H proton are in the same group, then we can determine the relative strength of acids based on the length of the bond. If the bond length is longer it is weaker and therefore easier to lose the H proton and a stronger acid.

[Barbara Soliman 1G]

How come we don't point to electronegativity when looking at atoms in the same group since as you go down the group the elements become less electronegative?