This exam tips covers Exam Tips for Acids and Alkalis within Acids and Alkalis for GCSE Chemistry. Revise Acids and Alkalis in Chemical Changes for GCSE Chemistry with 25 exam-style questions and 21 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 11 of 12 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
💡 Exam Tips for Acids and Alkalis
🎯 Common Question Types:
- Identify the ion responsible for acidity or alkalinity (1 mark)
- State the colour of an indicator in a given solution (1-2 marks)
- Write equations showing acids ionising in water (1-2 marks)
- Explain difference between strong/weak acids (HT, 3 marks)
- Describe how to measure pH in an experiment (2-3 marks)
📝 Key Command Words:
- Name the ion: Always answer H⁺ for acidity, OH⁻ for alkalinity
- Write an equation: Show the acid releasing H⁺ with a forward arrow (→)
- Explain: Reference the concentration of H⁺ ions and how pH is affected
- Compare: Strong/weak is about ionisation; concentrated/dilute is about amount dissolved
⚠️ Common Mistakes to Avoid:
- Confusing strong/weak with concentrated/dilute — completely different properties
- Saying "pH 7 means no ions present" — equal H⁺ and OH⁻ concentrations, not zero
- Using pH meters and universal indicator interchangeably — pH meters are more accurate
- Forgetting that all alkalis are bases, but not all bases are alkalis
- Writing H₂ instead of H⁺ as the acidic ion
Practice questions for Acids and Alkalis
Which ion do acids produce when dissolved in water?
Explain the difference between a strong acid and a concentrated acid.
Quick recall flashcards
Name two common alkalis
Sodium hydroxide (NaOH), Potassium hydroxide (KOH)
What is universal indicator?
An indicator that shows a range of colours across the pH scale (rainbow of colours from red to purple)