Acid-Base Chemistry
Acid-base chemistry covers proton transfer reactions, pH calculations, buffers, and titrations. Master strong/weak acid-base calculations, equilibrium constants, and buffer design.
Key Concepts
Study Tips
- ✓For strong acids/bases, [H+] or [OH-] equals initial concentration
- ✓For weak acids, use Ka equilibrium expressions or quadratic formula
- ✓pH + pOH = 14 at 25 degrees Celsius
- ✓At the equivalence point of a strong acid-strong base titration, pH = 7
Common Mistakes to Avoid
Students often confuse Ka and Kb with Kw, forget that weak acid/base calculations require equilibrium expressions, use the wrong formula for buffer pH (use Henderson-Hasselbalch!), and misidentify equivalence points on titration curves.
Acid-Base Chemistry FAQs
Common questions about acid-base chemistry
Set up the Ka equilibrium expression: Ka = [H+][A-]/[HA]. For weak acids where Ka << initial concentration, approximate [H+] = sqrt(Ka x C). If x is more than 5% of C, use the quadratic formula instead.
pH = pKa + log([A-]/[HA]) for acid buffers, or pOH = pKb + log([BH+]/[B]) for base buffers. It's used to calculate buffer pH and to determine ratios needed to prepare buffers at specific pH values.
Buffers contain a weak acid and its conjugate base (or weak base and conjugate acid). When H+ is added, the base component neutralizes it. When OH- is added, the acid component neutralizes it. This maintains relatively constant pH.