Cracking

Question 1

what is cracking?

Answer 1

• crude oil tends to contain much more longer alkanes than shorter ones
• unfortunately, the shorter ones are much more useful
• to get around this, we take the longer alkanes and do cracking

Question 2

what does cracking do?

Answer 2

cracking breaks down longer alkanes into smaller, more useful ones

Question 3

what are the conditions for cracking?

Answer 3

cracking is conducted under the following conditions:

• temperature: 650 degrees C
• catalyst: aluminium oxide (Al2O3)
  (it can be conducted without a catalyst but far more energy would need to be provided)

Question 4

what are the products of cracking?

Answer 4

cracking can produce a variety of products, but nearly always it works like this:

long alkane → shorter alkane + alkene

Question 5

example: what is the full equation for cracking pentane (C5H12)?

Answer 5

pentane (C5H12) → ethane (C2H6) + propene (C3H6)

Question 6

what are the two key features of cracking?

Answer 6

• it makes an alkane and an alkene
• the numbers of C and H atoms add up