Study Notes
Acids and bases can be defined by different theories, such as the Lewis theory and Brønsted-Lowry theory, which describe acids and bases based on their ability to donate or accept protons or electron pairs. The behavior of acids and bases in solution can be analyzed through titrations and pH curves, which provide insights into their strength and the formation of buffer solutions.
- Lewis Acid — an electron pair acceptor Example: Boron trifluoride (BF3) accepts an electron pair from ammonia (NH3).
- Lewis Base — an electron pair donor Example: Ammonia (NH3) donates an electron pair to boron trifluoride (BF3).
- Brønsted-Lowry Acid — a species that can donate a proton Example: Hydrogen chloride (HCl) donates a proton to form H+ and Cl- ions.
- Brønsted-Lowry Base — a species that can accept a proton Example: Hydroxide ion (OH-) accepts a proton to form water.
- Weak Acid — an acid that partially dissociates in solution Example: Ethanoic acid (CH3COOH) partially dissociates to form CH3COO- and H+.
- Buffer Solution — a solution that resists changes in pH when small amounts of acid or base are added Example: A mixture of ethanoic acid and sodium ethanoate.
Exam Tips
Key Definitions to Remember
- Lewis Acid: Electron pair acceptor
- Lewis Base: Electron pair donor
- Brønsted-Lowry Acid: Proton donor
- Brønsted-Lowry Base: Proton acceptor
- Weak Acid: Partially dissociates in solution
- Buffer Solution: Resists changes in pH
Common Confusions
- Confusing Lewis acids with Brønsted-Lowry acids
- Misunderstanding the role of conjugate acid-base pairs in buffers
Typical Exam Questions
- What is a Lewis acid? An electron pair acceptor
- How does a buffer solution work? It resists changes in pH by using a weak acid and its conjugate base
- What happens at the equivalence point in a titration? The amount of acid equals the amount of base
What Examiners Usually Test
- Understanding of acid-base theories
- Ability to interpret pH curves and titration data
- Knowledge of buffer solutions and their applications