Introduction
Acids and bases are fundamental to chemistry — they appear in every WAEC, JAMB, and NECO Chemistry paper. Understanding them deeply will earn you marks across multiple questions.
Defining Acids and Bases
Arrhenius Definition
An acid is a substance that produces H⁺ ions in water. A base produces OH⁻ ions in water. Simple, but limited.
Brønsted-Lowry Definition
More broadly: an acid is a proton donor, and a base is a proton acceptor. This covers reactions that don't involve water.
The pH Scale
pH measures how acidic or basic a solution is, on a scale of 0–14:
- pH 0–6: Acidic
- pH 7: Neutral
- pH 8–14: Basic (alkaline)
pH = -log[H⁺]. If [H⁺] = 0.01 mol/L, then pH = -log(0.01) = 2
Strong vs Weak Acids
Strong acids (HCl, H₂SO₄, HNO₃) fully dissociate in water. Weak acids (ethanoic acid, carbonic acid) only partially dissociate. This distinction is crucial for calculations!
Neutralization Reactions
Acid + Base → Salt + Water. Example:
HCl + NaOH → NaCl + H₂O
This is the basis of titration — know this cold for your practical exams.
Exam Tips
- Memorize the strong acids — everything else is weak
- Know indicators: litmus (red in acid/blue in base), phenolphthalein (colorless in acid/pink in base)
- Practice pH calculations until they feel automatic
- Buffers often appear in theory questions — understand how they resist pH change
Conclusion
Acids and bases are everywhere — in your stomach, in rain, in cleaning products. When you connect exam content to the real world, it sticks better. Master the definitions, the pH scale, and neutralization, and chemistry becomes much friendlier!
