Study Notes
Acids and bases have characteristic properties that can be identified by their reactions and effects on indicators. Acids produce H+ ions in aqueous solutions, while bases produce OH- ions. The pH scale measures the acidity or alkalinity of a solution, with values less than 7 being acidic, greater than 7 being alkaline, and exactly 7 being neutral.
- Acid — A substance that donates protons (H+ ions) in a solution. Example: Hydrochloric acid (HCl) dissociates completely in water.
- Base — A substance that accepts protons (H+ ions) in a solution. Example: Sodium hydroxide (NaOH) dissociates to release OH- ions.
- pH Scale — A scale used to measure the acidity or alkalinity of a solution. Example: A solution with pH 3 is acidic, while pH 9 is alkaline.
- Strong Acid — Completely dissociates in aqueous solution to release ions. Example: Sulfuric acid (H2SO4).
- Weak Acid — Partially dissociates in aqueous solution to release ions. Example: Ethanoic acid (CH3COOH).
- Strong Base — Fully dissociates in aqueous solution to release OH- ions. Example: Potassium hydroxide (KOH).
- Weak Base — Partially dissociates in aqueous solution to release OH- ions. Example: Ammonia (NH3).
Exam Tips
Key Definitions to Remember
- Acids are proton donors.
- Bases are proton acceptors.
- pH scale measures acidity and alkalinity.
Common Confusions
- Strong vs. concentrated: Strong refers to ion dissociation, concentrated refers to amount of substance.
- Acid reactions don't always result in neutralization.
Typical Exam Questions
- What is the pH of a neutral solution? pH 7
- How does a strong acid differ from a weak acid? Strong acids completely dissociate in solution, while weak acids partially dissociate.
- What happens to red litmus paper in an alkaline solution? It turns blue.
What Examiners Usually Test
- Understanding of the pH scale and its implications.
- Ability to differentiate between strong and weak acids and bases.
- Reactions of acids with metals, bases, and carbonates.