Cracking Hydrocarbons

• Longer chain hydrocarbons can be broken down into shorter , more useful hydrocarbons - This process is called cracking
• What happens during catalytic cracking?

  The hydrocarbons are heated until they vaporise - The vapour is passed over a hot catalyst - A thermal decomposition reaction then takes place - the products include alkanes and alkenes
• What is the word equation for catalytic cracking?

  Long-chain alkane ( + heat + a catalyst ) ---> short-chain alkane + alkene
• Write the equation for the cracking of decane

  decane ( + heat + a catalyst ) --> octane + ethene - This can be written as : C₁₀H₂₂ --> C₈H₁₈ + C₂H₄
• Write the symbol equation for the cracking of octane?

  C₈H₁₈ --> C₆H₁₄ + C₂H₄
• During steam cracking , hydrocarbons are mixed with steam and heated to a high temperature
• Some of the products of cracking are useful as fuels
• Why is there a high demand for fuels with small chains of carbon atoms?

  They are easy to ignite , and have low boiling points
• Alkanes can be used to make a range of new compounds , including polymers and industrial alcohol