Summary
Acids and bases have characteristic properties, including their reactions and effects on indicators. Acids are proton donors, while bases are proton acceptors.
- Acid — a substance that donates protons (H+ ions) in solution.
Example: Hydrochloric acid (HCl) donates protons to form chloride ions. - Base — a substance that accepts protons (H+ ions) in solution.
Example: Sodium hydroxide (NaOH) accepts protons to form water. - Strong Acid/Base — completely dissociates into ions in solution.
Example: Sulfuric acid (H2SO4) is a strong acid that fully dissociates. - Weak Acid/Base — partially dissociates into ions in solution.
Example: Ethanoic acid (CH3COOH) is a weak acid that partially dissociates. - Neutralization — a reaction where an acid and a base form water and a salt.
Example: HCl + NaOH → NaCl + H2O. - Indicator — a substance that changes color to indicate the pH of a solution.
Example: Litmus paper turns red in acid and blue in base.
Exam Tips
Key Definitions to Remember
- Acids are proton donors.
- Bases are proton acceptors.
- Strong acids/bases fully dissociate in water.
- Weak acids/bases partially dissociate in water.
Common Confusions
- Strong vs. concentrated: strength refers to ion dissociation, concentration refers to the amount of substance.
- Neutralization always produces water and a salt, but not all acid reactions are neutralizations.
Typical Exam Questions
- What is a neutralization reaction?
A reaction between an acid and a base producing water and a salt. - How does litmus paper indicate acidity?
Red litmus stays red in acid, blue litmus turns red in acid. - What happens when acids react with metals?
They produce a salt and hydrogen gas.
What Examiners Usually Test
- Understanding of pH scale and its relation to acidity and alkalinity.
- Ability to write balanced chemical equations for reactions involving acids and bases.
- Knowledge of the differences between strong and weak acids/bases.