Theories of acids and bases
2 marks · EasyDescribe how the hydroxonium ion, H_3O^+, forms when an acid is added to water, and explain its importance in acid–base reactions.
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Common mistakes: Vague answer, missing role in reactions
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Marking points
M1 · 1 mark · Describes that the acid donates a proton (H^+) to water to form H_3O^+.
M2 · 1 mark · Explains that H_3O^+ acts as the actual form of the hydrogen ion in solution and donates protons in acid–base reactions.
Worked solution
When an acid dissolves in water, it donates a proton (H^+) to a water molecule, forming H_3O^+.
This ion, H_3O^+, is important as it donates protons to bases during acid–base reactions, acting as the acidic particle in solution.