pH and pKa
- If you know the pH and pKa on an environment, you can know the ratio of [A-]/[HA]
○ If the ratio of [A-]/[HA] is > 1 → [HA] < [A-] & pH > pKa,
○ If the ratio of [A-]/[HA] is < 1 → [HA] > [A-] & pH < pKa
Acid-Base Indicators
- Indicators are used in titrations to indicate when we have passed the equivalence point
○ Are weak acids that change color when they become conj. bases
- Indicators have a “useful range” → have kA and pKa values
- Useful indicator range =
○ Best indicator to choose for a titration will be the one whose useful range includes or is closest to the pH at equivalence → color change will occur closest to eq. point