Reactions of acids
Cambridge IGCSE Chemistry (0620) · Unit 7: Acids, bases and salts · 10 flashcards
Reactions of acids is topic 7.2 in the Cambridge IGCSE Chemistry (0620) syllabus , positioned in Unit 7 — Acids, bases and salts , alongside Acids and bases, Preparation of salts and Oxides. In one line: Amphoteric oxides can react with both acids and bases to produce a salt and water. This dual reactivity distinguishes them from acidic or basic oxides.
This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical).
The deck below contains 10 flashcards — 2 definitions, 2 key concepts and 3 identification cards — covering the precise wording mark schemes reward. Use the 2 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.
The defining characteristic of an amphoteric oxide
Amphoteric oxides can react with both acids and bases to produce a salt and water. This dual reactivity distinguishes them from acidic or basic oxides.
What the Cambridge 0620 syllabus says
Official 2026-2028 specThese are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.
- Classify Classify oxides as acidic, including SO2 and CO2, or basic, including CuO and CaO, related to metallic and non-metallic character
- Describe Describe amphoteric oxides as oxides that react with acids and with bases to produce a salt and water Supplement
- Classify Classify Al2O3 and ZnO as amphoteric oxides Supplement
Classify sulfur dioxide (SO₂) as acidic, basic, or amphoteric.
Sulfur dioxide (SO₂) is classified as an acidic oxide due to its non-metallic character. Acidic oxides react with bases to form a salt and water.
Classify copper(II) oxide (CuO) as acidic, basic, or amphoteric.
Copper(II) oxide (CuO) is classified as a basic oxide due to its metallic character. Basic oxides react with acids to form a salt and water.
What is the defining characteristic of an amphoteric oxide?
Amphoteric oxides can react with both acids and bases to produce a salt and water. This dual reactivity distinguishes them from acidic or basic oxides.
Name two amphoteric oxides.
Aluminium oxide (Al₂O₃) and zinc oxide (ZnO) are examples of amphoteric oxides, which react with both acids and bases.
Write a balanced chemical equation for the reaction of aluminium oxide (Al₂O₃) with hydrochloric acid (HCl).
Al₂O₃(s) + 6HCl(aq) → 2AlCl₃(aq) + 3H₂O(l). Note the state symbols (s - solid, aq - aqueous, l - liquid) are important.
Write a balanced chemical equation for the reaction of aluminium oxide (Al₂O₃) with sodium hydroxide (NaOH).
Al₂O₃(s) + 2NaOH(aq) + 3H₂O(l) → 2NaAl(OH)₄(aq). Note the state symbols (s - solid, aq - aqueous, l - liquid) are important.
What are the state symbols used in chemical equations and what do they represent?
The state symbols are (s) for solid, (aq) for aqueous (dissolved in water), (l) for liquid, and (g) for gas. These symbols indicate the physical state of each substance in the reaction.
25.0 cm³ of 0.400 mol/dm³ hydrochloric acid reacts completely with a metal carbonate. Calculate the moles of HCl used.
Moles of HCl = (Volume in dm³ x Concentration) = (25.0/1000) x 0.400 = 0.0100 mol. Remember to convert cm³ to dm³ by dividing by 1000.
If 0.0100 mol of HCl reacts with a metal carbonate (MCO₃) according to the equation MCO₃ + 2HCl → MCl₂ + H₂O + CO₂, how many moles of CO₂ are produced?
From the balanced equation, 2 moles of HCl produce 1 mole of CO₂. Therefore, moles of CO₂ = 0.0100 / 2 = 0.00500 mol.
If 0.00500 mol of CO₂ is produced in a reaction, and the molar volume of a gas is 24000 cm³/mol, calculate the volume of CO₂ produced.
Volume of CO₂ = (Moles of CO₂ x Molar Volume) = 0.00500 x 24000 = 120 cm³. Make sure units are consistent.
Key Questions: Reactions of acids
What is the defining characteristic of an amphoteric oxide?
Amphoteric oxides can react with both acids and bases to produce a salt and water. This dual reactivity distinguishes them from acidic or basic oxides.
What are the state symbols used in chemical equations and what do they represent?
The state symbols are (s) for solid, (aq) for aqueous (dissolved in water), (l) for liquid, and (g) for gas. These symbols indicate the physical state of each substance in the reaction.
Tips to avoid common mistakes in Reactions of acids
- ● Understand that concentration impacts reaction rate via collision frequency: more particles in the same volume, more collisions.
- ● Consider both what a metal does and does not react with to gauge its reactivity.
- ● Learn common applications: aluminium is used where lightness and corrosion resistance are key, stainless steel for its strength and resistance to rust.
- ● Create a table summarizing the reactions of common metals (Ca, Mg, Zn, Fe, Cu) with water, steam, and dilute acids, linking it to the metal reactivity series.
- ● In limiting reactant problems, identify the limiting reactant first, and use *its* moles for subsequent calculations.
More topics in Unit 7 — Acids, bases and salts
Reactions of acids sits alongside these Chemistry decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 0620 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Key terms covered in this Reactions of acids deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
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