CHAP 15 FUELS & CRUDE OIL

Question 1

what are fuels?

Answer 1

substances which burn easily in air to give energy

Question 2

3 main sources of fuel

Answer 2

coal
petroleum ( crude oil )
natural gas ( methane CH4)

Question 3

properties of FOSSIL FUELS [2]

Answer 3

• remains from plants and animals that lived a million years ago
• non-renewable / limited and will be used up one day

Question 4

alternative fuels [2]

Answer 4

1) Hydrogen
- burns cleanly to produce H20 as only waste product which is non-polluting
- renewable energy -> can be obtained by electrolysis of seawater
2H2 (g) + O2 -> 2H20 (g)
2) Ethanol as BIOFUEL ( obtained from sugar cane - renewable source )
- ethanol often used as a fuel for cars
- biofuels are alternative renewable sources to crude oil and natural gas
- can be produced from the fermentation of plants ( sugar cane ) -> bioethanol

Question 5

Petroleum ( Crude oil ) [2]

Answer 5

• dark brown viscous liquid consisting of a mixture of hydrocarbons ( compounds containing hydrogen and carbon ONLY )
• little use before its refined -> necessary to separate into useful fractions by fractional distillation

Question 6

how is petroleum/crude oil separated in an oil refinery?

Answer 6

1) Fractional distillation is used to separate the petroleum into useful fractions based on their DIFFERENCE in BOILING POINTS
2) petroleum is heated in a furnace to become a VAPOUR
3) vapour moves up fractionating column. Column is cooler at the top than the bottom. Each fraction condenses at a DIFFERENT TEMPERATURES in the fractionating column at DIFFERENT HEIGHT.
4) the LOWER BOILING POINT FRACTIONS condense and are removed at the TOP while the HIGHER BOILING POINT FRACTIONS condense and are removed from the bottom.

Question 7

what are the 7 types of fuels separated in a FRACTIONAL DISTILLATION? ( IN ORDER )
( Little Pretty Girl Punches Noisy Purple Dinosaur Like Barney )

Answer 7

1) LPG - liquified petroleum gas [ used for cooking ]
2) Petrol ( gasoline ) [ fuels in cars ]
3) Naphtha [ feedstock for chemical industry ]
4) Kerosene ( Paraffin ) - used for aircrafts/jet
5) Diesel - fuel in diesel engines of buses & lorries
6) Lubricating oil - lubricants making waxing & polishes
7) bitumen - making roads

Question 8

top of the fraction is the coolest while bottom of the fraction is hottest.
properties of heavier fractions [2]

Answer 8

• bigger molecules, more viscous, have higher boiling points and burn less easily with a smokier flame
• heavier fractions are not so useful/ less in demand can go through CATALYTIC CRACKING to obtain lighter fractions such as petrol which is in greater demand.