This topic summary covers Topic Summary: Cracking within Cracking (HT) for GCSE Chemistry. Revise Cracking (HT) in Organic Chemistry for GCSE Chemistry with 24 exam-style questions and 0 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 14 of 14 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 14 of 14
Practice
24 questions
Recall
0 flashcards
Topic Summary: Cracking
Key Terms
- Cracking — thermal decomposition of long alkanes
- Products — shorter alkane + alkene (always)
- Thermal cracking — high T (700-900°C) + high P
- Catalytic cracking — lower T, zeolite catalyst
Bromine Water Test
- Orange bromine water + alkene → colourless
- Orange bromine water + alkane → stays orange
- Addition reaction across C=C double bond
Equation Balancing
- Count C atoms: must balance
- Count H atoms: must balance
- Alkene check: CₙH₂ₙ formula
- Always at least one alkene product
Why Crack?
- More petrol (high demand)
- More alkenes for polymers
- Low-value → high-value products
- Match supply to demand