Fuels

Question 1

what are the fossil fuels

Answer 1

coal, oil and natural gas

Question 2

what are non-renewable resources

Answer 2

those that are used faster than they can be replaced

Question 3

why are fossil fuels non-renewable

Answer 3

reserves of fossil fuels are limited and could eventually be exhausted

Question 4

what are fossil fuels

Answer 4

non-renewable fuels that are derived from plant or animal matter

Question 5

process of coal formation

Answer 5

1. plants that die in ancient wetlands are only partially decomposed due to anaerobic and acidic conditions, forming peat
2. Peat is buried under layers of sediment due to rising sea levels. the buried peat is subjected to heat and pressure
3. After millions of years of heat and pressure, coal is formed
   4.Coal is mined from the ground to be combusted in power plants for electricity

Question 6

what is coal composed of

Answer 6

primarily carbon (and water)

Question 7

“crude”

Answer 7

not refined

Question 8

distillation

Answer 8

boiling to evaporate and then condensing into a liquid

Question 9

coal burning reaction

Answer 9

C(s) + O2(g) = CO2 (g) (+ 32KJg-1)

Question 10

what happens as we go down the layers of coal

Answer 10

the water content decreases and carbon content increases which results in the increase of energy content of the coal

Question 11

why does less water in coal result in a higher energy conetnt

Answer 11

less water is needed to be vaporised, therefore the amount of heat released is greater

Question 12

why does energy content increase with coal content in carbon

Answer 12

the more heat is released when is it burned

Question 13

what is the overall efficiency of a coal-fired power station and why

Answer 13

30-40%, energy is lost in each step of the process (the more energy transformations, the less efficient the process)

Question 14

steps in the formation of oil and natural gas

Answer 14

1. ancient sea animals and plants die and their bodies fall to the sea floor, where anaerobic conditions prevent complete decomposition 2. plant and animal remains are covered by layers of sediment and subjected to heat and pressure over millions of years 3. after millions of years, oil and gas deposits are formed

Question 15

natural gas

Answer 15

composed of mainly methane together with small amounts of ethane and propane, (water, sulfur, carbon dioxide and nitrogen may be present)

Question 16

equation of the combustion of methane (natural gas)

Answer 16

CH4(g) + 2O2(g) = CO2(g) + 2H2O (l)

Question 17

where is natural gas found

Answer 17

natural gas deposits are often found trapped above crude oil, once a well is sunk into the deposit, the natural gas flows to the surface

Question 18

crude oil

Answer 18

a thick, sticky black liquid which is composed of a complex mixture of lots of different hydrocarbon compounds of different sizes

Question 18

where is crude oil found

Answer 18

in pourous rock (under the ground and under the sea)

Question 19

why is crude oil a finite resource?

Answer 19

it is being used up much faster than it is being formed

Question 20

how is crude oil converted into a useable form

Answer 20

it must be fractionally distilled and then cracked to obtain useful fuels such as petrol