Cracking breaks C-C bonds using heat and/or catalysts:
What Happens During Cracking:
• Long alkane molecules are heated until C-C bonds break
• Random breaking produces chains of different lengths
• Some products are shorter alkanes (saturated)
• Some products are alkenes (unsaturated — contain C=C bonds)
• The process is called thermal decomposition
• Long alkane molecules are heated until C-C bonds break
• Random breaking produces chains of different lengths
• Some products are shorter alkanes (saturated)
• Some products are alkenes (unsaturated — contain C=C bonds)
• The process is called thermal decomposition
Example: Cracking Decane (C₁₀H₂₂)
C₁₀H₂₂ → C₅H₁₂ + C₅H₁₀
decane → pentane + pentene
• One alkane broken into one shorter alkane + one alkene
• The alkene has a C=C double bond (unsaturated)
C₁₀H₂₂ → C₅H₁₂ + C₅H₁₀
decane → pentane + pentene
• One alkane broken into one shorter alkane + one alkene
• The alkene has a C=C double bond (unsaturated)
This deep dive covers The Chemistry of Cracking within Cracking (HT) for GCSE Chemistry. Revise Cracking (HT) in Organic Chemistry for GCSE Chemistry with 24 exam-style questions and 15 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 2 of 14 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Cracking (HT)
What is cracking in chemistry?
Describe the conditions used in thermal cracking and state the types of product formed.
Quick recall flashcards
Why is cracking needed?
Long alkanes are less useful. Cracking produces shorter alkanes for fuel and alkenes for polymers
What is cracking?
Breaking down long-chain hydrocarbons into shorter, more useful molecules