Case study·Standard multi-step (3/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
During a practical exam, a student prepares a standard oxalic acid solution, fills the burette with and titrates it against the oxalic acid in a conical flask. The student leaves the funnel on the burette, notices an air bubble in the burette jet after taking the initial reading, and uses a wet conical flask.
Total: 4 marks
(a) Why should the funnel be removed before titration? (1 mark)
(b) What should be done about the air bubble before taking the initial reading? (1 mark)
(c) Does a wet conical flask necessarily change the moles of oxalic acid pipetted into it? (1 mark)
(d) Name the self-indicator in this titration. (1 mark)
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