Fuels and Earth Science

Question 1

what are the different fossil fuels

Answer 1

coal
crude oil
natural gas

Question 2

what are fossil fuels

Answer 2

non-renewable resources

Question 3

what are hydrocarbons

Answer 3

compounds that contain hydrogen and carbon only

Question 4

what is crude oil an important source of

Answer 4

fuels for vehicles, aircraft, ships, heating and power stations

feedstock or raw materials for the petrochemical industry

Question 5

what is fuel

Answer 5

a substance that produces heat energy when it burns

Question 6

why should we use biodiesel rather than petrol and diesel

Answer 6

saves fossil fuels
it is made from crops like sugarcane which are renewable
biodiesel is almost carbon neutral

Question 7

what does the incomplete combustion of hydrocarbons produce

Answer 7

carbon(soot)
carbon monoxide
water

Question 8

what two gases cause acid rain

Answer 8

sulfur dioxide and nitrogen dioxide

Question 9

what are the renewable sources of energy

Answer 9

solar power, tidal power, wind power, geothermal power

Question 10

why can using only renewable sources of energy cause problems in the supply of electricity

Answer 10

many renewable energy supplies cannot generate electricity all the time and some energy supplies are unreliable/unpredictable

Question 11

how is crude oil separated into simples, more useful mixtures

Answer 11

by fractional distillation because the different hydrocarbons in crude oil have different boiling points

Question 12

what is a fraction

Answer 12

a group of molecules with similar boiling points and similar numbers of carbon and hydrogen atoms

Question 13

how does fractional distillation work

Answer 13

crude oil is heated strongly to evaporate it, and the hot vapours are piped into the bottom of the column. The vapours rise through the column and cool down. Liquids of different boiling points condense at different temperatures and are piped away. Bitumen has the highest boiling point and leaves at the bottom as a hot liquid

Question 14

what are the uses of petrol

Answer 14

it is used as fuel for cars

Question 15

what is the use of kerosene

Answer 15

it is used as fuel for aircraft

Question 16

what is the use of diesel oil

Answer 16

fuel for some cars and trains

Question 17

what is the use of fuel oil

Answer 17

fuel for large ships and in some power stations

Question 18

what is the use of bitumen

Answer 18

used to surface roads and roofs

Question 19

why is a range boiling points given for each fraction

Answer 19

each fraction is a mixture of compounds
each compond has a different boiling point

Question 20

how can you conclude that each fraction is a mixture of compounds and not a single compound

Answer 20

the fraction boils over a range of temperatures

Question 21

what are the properties of the smaller hydrocarbon molecules

Answer 21

lower boiling point
low viscosity (flow easily)
easier to ignite

Question 22

what is the test for carbon dioxide

Answer 22

bubble the gas into limewater and the limewater turns cloudy

Question 23

what is the chemical test for water

Answer 23

add water to anhydrous copper sulfate and it goes from white to blue

Question 24

what is the physical test for water

Answer 24

measure the boiling point of water, pure water boils at 100 degrees

Question 25

what is carbon monoxide dangerous

Answer 25

it combines with haemoglobin in red blood cells, preventing oxygen from binding with haemoglobin. This reduces the amount of oxygen in the bloodstream causing affected people to become unconscious or even die

Question 26

how is sulfur dioxide produced

Answer 26

it is formed when hydrocarbon fuels containing sulfur are burned. When the fuel is burnt, the sulfur reacts in the air to produce sulfur dioxide.

Question 27

how are oxides of nitrogen produced

Answer 27

when fuels are burned in engines, nitrogen and oxygen in the air inside the engine react together due to the high temperatures in the engine producing different oxides of nitrogen.

Question 28

what does acid rain do

Answer 28

it kills crops, makes rivers acidic and kills fish, weathers structures made of limestone and marble, corrodes metal structures and weakens them

Question 29

what are the benefits of using hydrogen to fuel cars

Answer 29

the combustion of hydrogen only produces water hydrogen is easily ignited and its combustion releases large amounts of energy

Question 30

what are the negatives of using hydrogen to fuel cars

Answer 30

hydrogen is a gas at room temperature which makes it difficult to store in large amounts and so it has to be compressed under high pressure there could be a risk of an explosion since hydrogen is highly flammable it is expensive to produce hydrogen from water by electrolysis

Question 31

what is the general formula for alkanes

Answer 31

CnH2n+2

Question 32

are alkanes saturated or unsaturated hydrocarbons

Answer 32

saturated

Question 33

What happens in cracking

Answer 33

the large alkane is heated to evaporate it. The vapours are then passed over a catalyst of aluminium oxide and heated to about 650 degrees. The alkane is thermally decomposed and smaller, more useful hydrocarbons form and these could be used as fuels or for making polymers

Question 34

why do we do cracking

Answer 34

it produces smaller alkanes which are better fuels as they are easier to ignite it produces alkenes which are needed to make polymers it produces smaller, more useful products

Question 35

what can cracking produce

Answer 35

alkane + alkene OR 2 alkenes + H2

Question 36

what is the catalyst used in cracking

Answer 36

broken porcelain / aluminium oxide

Question 37

what are the conditions needed for cracking

Answer 37

high temperature and a catalyst

Question 38

Saturated

Answer 38

molecules are saturated if all the carbon-carbon covalent bonds are single bonds

Question 39

what are the first 5 alkanes

Answer 39

methane ethane propane butane pentane

Question 40

why do alkanes have low boiling points

Answer 40

They have a simple molecular structure. They are made up of small molecules with weak forces between molecules and not much energy is needed to break these weak intermolecular forces.

Question 41

what are the characteristics of a homologous series

Answer 41

they have the same general formula they have similar chemical properties they differ by CH2 in molecular formulae from neighbouring compounds

Question 42

isomers

Answer 42

compounds with the same molecular formula but different structural formula

Question 43

what is the general formula for alkenes

Answer 43

CnH2n (n>2)

Question 44

are alkenes saturated or unsaturated hydrocarbons

Answer 44

unsaturated as the contain at least one carbon-carbon double bond

Question 45

what are the first 5 alkenes

Answer 45

ethene propene butene pentene hexene

Question 46

what happens in addition reactions

Answer 46

a molecule adds across the carbon-carbon double bond to give a single saturated product

Question 47

why do all addition reactions have an atom economy of 100%

Answer 47

only 1 product is formed

Question 48

what is the test for an alkene

Answer 48

add bromine water to the compound and shake. It goes from orange to colourless however an alkane would remain orange

Question 49

what is PTFE/teflon used for

Answer 49

to make non stick coatings for frying pans and kitchen utensils, burette taps and stain proofing clothing and carpets

Question 50

what are the advantages of polymers(plastics)

Answer 50

they are resistant to corrosion they are good insulators they can be moulded they are lighter than other materials

Question 51

what are the problems caused by non-biodegradable polymers

Answer 51

toxic gases are produced when polymers are burned there is a shortage of landfill sites there is a danger to wildlife it causes litter/visual pollution