Cracking

• What is meant by cracking in chemistry?

  Breaking down long chain hydrocarbons
• What are the conditions for cracking?

  High temperature and a catalyst or steam
• What is an alkene?

  A hydrocarbon with a double bond
• How can you test for alkenes?

  Using bromine water that turns colorless
• What is the general formula for alkanes?

  $C_nH_{2n+2}$
• Why are long chain hydrocarbons not good fuels?

  They are not very flammable
• What is the purpose of cracking hydrocarbons?

  To produce shorter, more useful hydrocarbons
• What is the structure of an alkane?

  Single covalent bonds between carbon atoms
• How does catalytic cracking differ from steam cracking?

  Catalytic uses a catalyst, steam uses steam
• How do you balance a chemical equation for cracking?

  Ensure carbon and hydrogen atoms are equal
• What is the product of cracking a long chain alkane?

  Shorter chain alkanes and alkenes
• If a cracking reaction has 25 carbon and 52 hydrogen atoms on the left, how many are on the right?

  20 carbon and 42 hydrogen atoms
• What must the second product molecule have if the first has 5 carbon and 10 hydrogen atoms?

  Must balance to 25 carbon and 52 hydrogen
• How many carbon and hydrogen atoms are in the first product if the left side has 40 carbon and 82 hydrogen?

  33 carbon and 68 hydrogen atoms
• What are the uses of alkenes?

  • Used to make polymers
  • Starting material for other chemicals
• What are the key features of alkanes?

  • General formula: $C_nH_{2n+2}$
  • Only single covalent bonds
• What happens to bromine water when it tests for alkenes?

  • Bromine water is orange
  • Turns colorless when shaken with alkene
• What is the process of cracking hydrocarbons?

  1. Break down long chain hydrocarbons
  2. Produce shorter, useful hydrocarbons
  3. Can produce alkenes