Basics of Cracking
What is cracking?
Breaking long-chain hydrocarbons into shorter molecules.
Complete the reaction:
C₁₀H₂₂ → C₆H₁₄ + ___
C₄H₈
Cracking can produce two alkanes.
False
Why do we perform cracking?
To produce more useful short-chain fuels like petrol.
C₈H₁₈ → C₄H₁₀ + ___
C₄H₈
Cracking always produces an alkene.
True
What two kinds of hydrocarbons form during cracking?
One alkane + one alkene.
Give one valid cracking reaction for C₆H₁₄.
Example: C₆H₁₄ → C₃H₈ + C₃H₆
Cracking is a random process.
False — it follows conservation of atoms.
Why do short-chain hydrocarbons burn more cleanly?
They ignite easily and have lower boiling points.
Crack C₁₂H₂₆ into two valid products.
C₈H₁₈ + C₄H₈
Alkenes are saturated hydrocarbons.
False — they contain C=C double bonds.
Why is cracking essential in petroleum refining?
Because crude oil contains too many long-chain molecules in low demand.
Why must one product of cracking be unsaturated?
Hydrogen atoms are insufficient to saturate both fragments → one becomes an alkene.
Alkanes and alkenes always have the same number of hydrogens.
False — alkenes have two fewer H atoms.
Explain why cracking helps balance fuel supply and demand.
It converts low-demand long-chain hydrocarbons into high-demand short-chain fuels.