Playbook
Alkanes
35 q - 0.92/paper - never HARD. Wurtz, decarboxylation and Grignard, and chain isomers.
- Questions in the bank
- 35
- q/paper (2024–25 papers)
- 0.92
- Tagged HARD
- 0%
- Subtopics
- 3
Strand: Reactions
When you’ll see it
An alkane made by coupling, decarboxylation or from a Grignard reagent — or chain isomers to count.
How this chapter is tested
35 q at 0.92 a paper and never a HARD question. Preparation (17 q) is three named routes: Wurtz (2RX + 2Na → R–R, the chain doubles), decarboxylation with soda-lime (RCOONa → RH, one carbon fewer), and Grignard reagents with water (RMgX + H₂O → RH).
Naming and isomers (14 q) count chain isomers — pentane has three — and read names off structures. Free-radical halogenation (4 q) is the substitution chain.
The sub-skills
The distinct skills inside the chapter, in the order to learn them.
Wurtz
2RX + 2Na → R–R: an odd-carbon alkane cannot come from a single halide.
Decarboxylation
RCOONa + NaOH/CaO → RH + Na₂CO₃ — one carbon fewer.
Chain isomers
Butane 2, pentane 3, hexane 5.
Traps to expect
Distractor shapes this chapter reuses. The Traps page covers the patterns that cut across chapters.
Counting carbons after decarboxylation
Sodium propanoate gives ethane, not propane.
Wurtz and odd chains
Propane cannot be made cleanly by Wurtz from one halide: mixing two halides gives a mixture of three alkanes.
Learn it before you drill it
This chapter has full teaching notes — foundations, worked examples, self-checks and a per-subtopic mastery checkpoint. Read the notes once, then drill subtopic by subtopic below.
Alkanes notesDrill every alkanes question
35 questions from the bank, scoped to 3 bundled subtopics.
Drill one subtopic at a time
The 3 subtopics this playbook covers, in catalog order.
Related playbooks
Often paired with this one — the technique, the trap or the taxonomy overlaps. Drill these next.