Q65 · Practice questionComplex familiar4 marks
QUESTION 65 (4 marks)
Three unlabelled vials contain hexane, hex-1-ene and hexan-1-ol. Small samples may be tested separately.
a) Design a two-test sequence to identify all three. Give expected observations. [4 marks]
WORKED SOLUTION
4 marksPractice marking scheme
Bromine water identifies hex-1-ene by rapid decolourisation without UV; acidified dichromate with heating identifies hexan-1-ol by orange-to-green change. Hexane gives neither change.
Use fresh portions. The alkene adds bromine under room conditions. The primary alcohol is oxidised by acidified dichromate. Hexane does not react under these specified mild test conditions.
- Selects bromine water without UV for the alkene. [1 marks]
- States alkene decolourises and others do not under those conditions. [1 marks]
- Selects heated acidified dichromate for the alcohol. [1 marks]
- States alcohol changes orange to green, leaving hexane identified. [1 marks]
Practice question aligned to the current QCAA syllabus; review the worked solution and marking criteria.
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