SC20f Breaking Down Hydrocarbons

Question 1

why is cracking necessary?

Answer 1

to increase the supply to meet the demand for certain fractions

Question 2

what type of hydrocarbons are alkanes? what does this mean as an effect on bromine water?

Answer 2

saturated carons with no C=c bonds
no effect on bromine water

Question 3

hydrocarbons are alkenes? what does this mean as an effect on bromine water?

Answer 3

unsaturated hydrocarbons with C=C bonds
turn bromine water colourless

Question 4

cracking?

Answer 4

chemical reaction in which large alkane molecules are split into 2 or more smaller alkanes and alkenes​

Question 5

after cracking what is the use of the smaller alkane?

Answer 5

for fuel

Question 6

after cracking what is the alkene used for?

Answer 6

to make polymers

Question 7

petrol advantages (4)and disadvantages (3) as a fuel in cars?

Answer 7

adv:
~liquid at rtp
~large amounts stored in fuel tanks
~easily ignited
~combustion releases lots of energy
dis:
~in high demand
~easily ignited
~combustion releases CO2 (greenhouse gas)

Question 8

advantages of hydrogen as a fuel in cars? 4

Answer 8

~by product of cracking
~easily ignited
~combustion releases large amounts of energy
~combustion releases water vapour only

Question 9

disadvantages of hydrogen as a fuel in cars? 5

Answer 9

~produced from methane and steam
~gas at rtp
~difficult to store large amounts as a gas
~has to be compressed or cooled for storage as a liquid
~easily ignited