Note:

2023/2024/2025 IGCSE Chemistry Notes on Acids Bases  Salts

Syllabus Content:

7.1 The characteristic properties of acids and bases IGCSE Chemistry

Core

1.  Describe the characteristic properties of acids in terms of their reactions with: (a) metals (b) bases (c) carbonates 
2. Describe acids in terms of their effect on: (a) litmus (b) thymolphthalein (c) methyl orange 
3. State that bases are oxides or hydroxides of metals and that alkalis are soluble bases 
4. Describe the characteristic properties of bases in terms of their reactions with: (a) acids (b) ammonium salts 
5. Describe alkalis in terms of their effect on: (a) litmus (b) thymolphthalein (c) methyl orange 
6. State that aqueous solutions of acids contain H+ ions and aqueous solutions of alkalis contain OH– ions 
7. Describe how to compare hydrogen ion concentration, neutrality, relative acidity and relative alkalinity in terms of colour and pH using universal indicator paper 
8. Describe the neutralisation reaction between an acid and an alkali to produce water, H+ (aq) + OH– (aq) → H2O(l)

Supplement 

1. Define acids as proton donors and bases as proton acceptors
2. Define a strong acid as an acid that is completely dissociated in aqueous solution and a weak acid as an acid that is partially dissociated in aqueous solution
3. State that hydrochloric acid is a strong acid, as shown by the symbol equation
4. State that ethanoic acid is a weak acid, as shown by the symbol equation
5. Describe how to compare hydrogen ion concentration, neutrality, relative acidity and relative alkalinity in terms of colour and pH using universal indicator paper 
6. Describe the neutralisation reaction between an acid and an alkali to produce water

7.2 Oxides IGCSE Chemistry

Core 

1. Classify oxides as acidic, including SO2 and CO2, or basic, including CuO and CaO, related to metallic and non-metallic character

Supplement

1. Describe amphoteric oxides as oxides that react with acids and with bases to produce a salt and water 
2. Classify Al 2O3 and ZnO as amphoteric oxides

7.3 Preparation of salts IGCSE Chemistry

Core

1. Describe the preparation, separation and purification of soluble salts by reaction of an acid with: (a) an alkali by titration (b) excess metal (c) excess insoluble base (d) excess insoluble carbonate
2. Describe the general solubility rules for salts: (a) sodium, potassium and ammonium salts are soluble (b) nitrates are soluble (c) chlorides are soluble, except lead and silver (d) sulfates are soluble, except barium, calcium and lead (e) carbonates are insoluble, except sodium, potassium and ammonium (f) hydroxides are insoluble, except sodium, potassium, ammonium and calcium (partially)
3. Define a hydrated substance as a substance that is chemically combined with water and an anhydrous substance as a substance containing no water Supplement
4. Describe the preparation of insoluble salts by precipitation 
5. Define the term water of crystallisation as the water molecules present in hydrated crystals, including CuSO4•5H2O and CoCl 2•6H2O

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