A-LevelChemistryAnalytical techniquesOct/Nov 2024Paper 5 Q217 Marks
Crystal violet, C25H30N3Cl(s), is a purple dye. Some light is absorbed when it passes through C25H30N3Cl(aq). Absorbance is the proportion of light absorbed at a particular wavelength. This is measured using a colorimeter. A graph of absorbance against wavelength for C25H30N3Cl(aq) is shown in [Figure 2.1]. A student investigates how to determine the concentration of aqueous crystal violet, C25H30N3Cl(aq), using colorimetry.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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