🎯 Common Question Types:
- Give the molecular formula of a named alkane (1 mark)
- Explain what "saturated" means (1-2 marks)
- Draw the displayed formula of propane (2 marks)
- Explain why butane has a higher boiling point than methane (2 marks)
📝 Key Command Words:
- Explain: Link to single bonds and forces between molecules
- Draw: Show each bond as a line, every C must have 4 bonds
- State: Give the formula or name directly
⚠️ Common Mistakes to Avoid:
- Saying saturated means "full of energy" — it means single bonds only
- Drawing carbon with more or fewer than 4 bonds
- Using CₙH₂ₙ (alkene formula) instead of CₙH₂ₙ₊₂
Quick Check: What is the molecular formula of pentane (an alkane with 5 carbons)?
Using CₙH₂ₙ₊₂ with n=5: H = 2(5)+2 = 12. Formula = C₅H₁₂.
Quick Check: Explain in one sentence what "saturated" means for an alkane.
A saturated hydrocarbon contains only single carbon-carbon bonds, meaning no double bonds are present and each carbon atom is bonded to the maximum possible number of hydrogen atoms.
This exam tips covers Exam Tips: Alkanes within Alkanes for GCSE Chemistry. Topic 38: Alkanes It is section 11 of 12 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Practice questions for Alkanes
What is the general formula for the alkane homologous series?
Explain why the boiling point of alkanes increases as the chain length increases.