Weak acids vs. weak bases

[Ann Pham]

If the common theme to identify weak bases is the presence of a nitrogen with a lone pair, is there a common theme to identify weak acids? Or is memorizing the strong bases/acids more effective?

[Chem_Mod]

This is not a universal common theme, there exist compounds with nitrogen lone pairs that are very strong bases. For this class you should memorize the list of seven strong acids:

HCl, HBr, HI
HClO3, HClO4
HNO3
H2SO4

Every hydroxide of a Group 1 or Group 2 metal is a strong base: eg. NaOH, KOH, Sr(OH)2, etc

Any acid/base not mentioned here can be safely assumed to be weak. The conjugate of a strong acid is a weak base and vice versa. The conjugate of a weak acid is a strong base and vice versa.