Study Notes
Acids and bases are chemical compounds that can donate or accept protons, respectively, as defined by the Brønsted-Lowry Theory. They exhibit distinct properties, such as reactivity with metals and the ability to change the pH of a solution. The pH scale measures the acidity or alkalinity of a solution, with strong acids and bases dissociating completely in water, while weak ones do so partially.
- Brønsted-Lowry Acid — A species that donates a proton (H⁺). Example: HCl donates a proton to water to form H₃O⁺.
- Brønsted-Lowry Base — A species that accepts a proton (H⁺). Example: NH₃ accepts a proton to form NH₄⁺.
- Conjugate Acid-Base Pair — Two species differing by a proton. Example: CH₃COOH and CH₃COO⁻.
- Amphiprotic — A species that can both donate and accept a proton. Example: Water can act as both an acid and a base.
- Amphoteric — A substance that can act as both an acid and a base. Example: Aluminum oxide reacts with both acids and bases.
- Neutralization — A reaction between an acid and a base forming water and a salt. Example: HCl + NaOH → NaCl + H₂O.
- pH Scale — A logarithmic scale measuring the acidity or alkalinity of a solution. Example: pH 7 is neutral, below 7 is acidic, above 7 is basic.
- Acid Deposition — The process by which acidic components leave the atmosphere. Example: Acid rain with a pH below 5.6.
Exam Tips
Key Definitions to Remember
- Brønsted-Lowry Acid: A proton donor
- Brønsted-Lowry Base: A proton acceptor
- Conjugate Acid-Base Pair: Two species differing by a proton
- Amphiprotic: Can donate and accept a proton
- Amphoteric: Can act as both an acid and a base
Common Confusions
- Amphiprotic vs. Amphoteric: Amphiprotic refers specifically to proton transfer, while amphoteric refers to acting as both an acid and a base
- Strong vs. Weak Acids/Bases: Strong acids/bases dissociate completely, while weak ones do not
Typical Exam Questions
- What is a Brønsted-Lowry acid? A species that donates a proton.
- How does the pH scale work? It measures the acidity or alkalinity of a solution, with 7 being neutral.
- What is the difference between strong and weak acids? Strong acids dissociate completely in water, while weak acids do not.
What Examiners Usually Test
- Understanding of acid-base theories
- Ability to predict products of acid-base reactions
- Calculation of pH and understanding of the pH scale
- Differences between strong and weak acids and bases