Chemical ChangesTopic Summary
Topic Summary: Acids and Alkalis
Part of Acids and Alkalis — GCSE Chemistry
This topic summary covers Topic Summary: Acids and Alkalis within Acids and Alkalis for GCSE Chemistry. Revise Acids and Alkalis in Chemical Changes for GCSE Chemistry with 20 exam-style questions and 20 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 12 of 12 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 12 of 12
Practice
20 questions
Recall
20 flashcards
Topic Summary: Acids and Alkalis
Key Terms
- Acid: releases H⁺, pH < 7
- Alkali: releases OH⁻, pH > 7
- Base: reacts with acid; alkalis are soluble bases
- pH 7: neutral (equal H⁺ and OH⁻)
- Indicator: shows pH by colour change
- Concentration: amount dissolved per volume
Must-Know Facts
- Three lab acids: HCl, H₂SO₄, HNO₃
- Two lab alkalis: NaOH, KOH
- Litmus: red in acid, blue in alkali
- Phenolphthalein: colourless → pink (acid → alkali)
- Methyl orange: red → yellow (acid → alkali)
- HT: strong acids fully ionise; weak acids partially ionise