CAIE A-Level Chemistry 7.2.4 Strong and Weak Acids and Bases

Practise distinguishing complete dissociation of strong acids or bases from partial dissociation of weak ones in water.

Exam points

define strong acids and bases by complete aqueous dissociation and weak ones by partial dissociation
write an equilibrium arrow for partial dissociation and avoid defining strength by concentration
explain weak-acid neutralisation data using the additional energy required for further ionisation

[Maximum number: 1]

Sulfides are compounds that contain sulfur but not oxygen.

Hydrogen sulfide gas, $\mathrm{H}_{2} \mathrm{~S}(\mathrm{~g})$ , is slightly soluble in water. It acts as a weak acid in aqueous solution.

State the meaning of weak acid.

weak [acid] partially dissociates/partially ionises (into $\mathrm{H}^{+}$ ions/protons)

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