Alkanes-Cracking

Question 1

Cracking

Answer 1

Involves breaking C-C bonds
(breaking long chain hydrocarbons into shorter chain hydrocarbons)

Question 2

Thermal cracking

Answer 2

• high temperature(up to 1000 cent degrees)
  -high pressure (up to 70 ATM)
• produces a lot of alkenes
  -alkenes used to make valuable products like polymers
  (e.g. polyethene made from ethene)

Question 3

Catalytic cracking

Answer 3

-zeolite catalyst sometimes used
(hydrated aluminosilicate)
-slight pressure
-high temperature(about 500cent degrees)
-mostly produces aromatic hydrocarbons and the alkanes needed to produce motor fuels
-Use of a catalyst reduces cost because reaction can be done at a lower temperature and at a lower pressure
-speeds up reaction saving time and money

Question 4

State 3 economic reasons for the cracking of petroleum fractions

Answer 4

-produces alkanes/ethene/propene/motor fuels/petrol
-makes useful products/higher value products
-satisfies the high demand for smaller products

Question 5

Property of molecules in petroleum that allows the mixture to be separated into different fractions

Answer 5

-molecules have different boiling points/ intermolecular forces/ sizes/chain lengths/Mr