Rules for acids (slide 1): 1. Acids like to lose their H+. The better the acids are at losing H+, the "stronger" of an acid they are, and the lower their pKa. 2. Take away the H+. Then evaluate how stable the compound is without the H+. 3. How do we evaluate stability of compounds? Look for: a. Charge b. Hybridization c. Atom d. Induction e. Resonance You can remember it as a CHAIR. 4. The most stable compound is the most acidic. In this example, the answer is iii<i<ii. Rules for bases (slide 2): 1. Bases like to accept an H+. The better the bases are at accepting an H+, the stronger of a base it is, and the higher it's pKa. 2. Evaluate how stable the molecule is with the criteria above. 3. The least stable compound (and therefore most likely to grab an H+) is the most basic. In this example, the answer is ii<iii<i.