A-LevelChemistryEquilibriaMay/June 2010Paper 1 Q121 Mark
Swimming pool water can be kept free of harmful bacteria by adding aqueous sodium chlorate(I), NaOCl. This reacts with water to produce HOCl molecules which kill bacteria. OCl⁻(aq) + H2O ⇌ OH⁻(aq) + HOCl(aq) In bright sunshine, the OCl⁻ ion is broken down by ultra-violet light. OCl⁻(aq) + uv light → Cl⁻(aq) + ½O2(g) Which method would maintain the highest concentration of HOCl(aq)?
Aacidify the pool water
Badd a solution of chloride ions
Cadd a solution of hydroxide ions
Dbubble air through the water
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The correct answer is A. This question tests the candidate's understanding of equilibria within the Chemistrysyllabus. The examiner's mark scheme requires...
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