Note:

Acids Bases and Salts  Notes Coordinated Sciences Chemistry / 2025/2026/2027 Exams

IGCSE Coordinated Science Chemistry students do not study the following information from the notes:

• Describe acids in terms of their effect on thymolphthalein
• Describe the characteristic properties of bases in terms of their reactions with:  ammonium salts
• Describe alkalis in terms of their effect on:  thymolphthalein 
• State that aqueous solutions of acids contain H+ ions and aqueous solutions of alkalis contain OH– ions
• Describe how to compare hydrogen ion concentration
• Describe the neutralisation reaction between an acid and an alkali to produce a salt and water[Note: Only  the ionic equation for this reaction is not required)
• Define acids as proton donors and bases as proton acceptors.
• 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
• State that hydrochloric acid is a strong acid, as shown by the symbol equation, HCl(aq) → H+ (aq) + Cl – (aq) 
• State that ethanoic acid is a weak acid, as shown by the symbol equation, CH3COOH(aq) ⇌ H+ (aq) + CH3COO– (aq)
• Describe how to compare hydrogen ion concentration, neutrality, relative acidity and relative alkalinity in terms of colour and pH using universal indicator paper
• Describe the neutralisation reaction between an acid and an alkali to produce water, H+ (aq) + OH– (aq) → H2O(l)
• 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
• The general solubility rules for salts are not required for insoluble salt preparation is not required.