What Is pK_a?

The pK_a measures how easily a compound loses a proton. Lower pK_a = stronger acid. These values are measured in water (not DMSO).

Factors That Increase Acidity

Electronegativity: More electronegative atoms stabilize the conjugate base better (e.g., O–H more acidic than C–H).
Resonance: If the conjugate base is resonance-stabilized, the acid is stronger (e.g., carboxylic acids, phenols).
Induction: Electron-withdrawing groups (halogens, carbonyls, nitro, cyano) pull electron density away, stabilizing the conjugate base.
Hybridization: More s-character holds electrons closer → sp > sp2 > sp3 acidity (e.g., terminal alkynes are more acidic than alkenes).
Solvent effects: Water stabilizes charged species through hydrogen bonding, so pK_a values in water differ from those in DMSO.

Compare two compounds and pick the one with the lower pK_a in water (not DMSO).

I don't know

Streak: 0 Best: 0

Correct: ... Incorrect: ...