This key facts covers Key Facts: Acids, Alkalis and Indicators 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 7 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
📌 Key Facts: Acids, Alkalis and Indicators
- Acids have pH less than 7 and produce H⁺ ions in solution
- Alkalis have pH greater than 7 and produce OH⁻ ions in solution
- Neutral substances have pH exactly 7 (equal H⁺ and OH⁻)
- Universal indicator shows a range of colours across the pH scale
- Litmus is red in acid, blue in alkali
- Phenolphthalein is colourless in acid, pink in alkali
- Methyl orange is red in acid, yellow in alkali
- The three common lab acids are: HCl, H₂SO₄, HNO₃
- The two common lab alkalis are: NaOH, KOH
- Concentrated = lots of acid/alkali particles per volume
- Dilute = few acid/alkali particles per volume
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)