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Question 1

what does cracking mean

Answer 1

cracking means splitting up long chain hydrocarbons by passing vapour over a hot catalyst

Question 2

if you were to crack a long chain molecule like diesel what 3 product would you get

Answer 2

1. petrol
2. parraffin
3. ethene for plastics

Question 3

cracking is a thermal decomposition reaction which breaks products down by…

Answer 3

heating them

Question 4

describe the process of cracking

Answer 4

the first step is to heat the long chain hydrocarbon to vaporise it (turn it into a gas), then the vapour is passed over a catalyst at 400-700 degrees Celsius (aluminium oxide is the catalyst used), then the long chain molecules crack on the surface of the specks of catalyst

Question 5

what bond does an alkene have

Answer 5

an alkene has a double bond

Question 6

what are alkenes

Answer 6

alkenes are hydrocarbons which have a double bond between two of the carbon atoms in their chain

Question 7

why are alkenes known as unsaturated

Answer 7

because they can make more bonds, the double bonds open up, allowing the two carbon atoms to bond with each other

Question 8

what are the first two alkenes

Answer 8

ethene (with two carbon atoms)and propene (with 3 carbon atoms)

Question 9

what is the general formula for alkenes

Answer 9

C(n)H(2n) (they have twice as many hydrogen atoms than carbon atoms

Question 10

what is the formula for ethene

Answer 10

C2H4

Question 11

what is tyeh formula for propene

Answer 11

C3H6

Question 12

how can you test for an alkene

Answer 12

you can test for an alkene by adding the substance to bromine water, an alkene will decolourise the bromine water turning it from orange to colourless, this is because the double bond has opened up and formed bonds with the bromine

Question 13

how is ethanol produced

Answer 13

ethene can be hydrated with steam in the presence of a catalyst to make ethanol

Question 14

what is the process in which ethanol that makes beer and wine is produced

Answer 14

fermentation

Question 15

what raw material is used for fermentation to make ethanol

Answer 15

sugar

Question 16

what is the word equation for sugar being converted into ethanol using yeast

Answer 16

sugar = carbon dioxide + ethanol

Question 17

what is polymerisation

Answer 17

this means joining together lots of small alkene molecules (monomers) to form very large molecules, these long chain molecules are called polymers

Question 18

many ethene molecules can be joined up to produce…

Answer 18

poly(ethene)/polythene

Question 19

what are the properties of poly(ethene) made at 200 d/c and 2000 atmospheres pressure

Answer 19

it is flexible, and has a low density

Question 20

what are the properties of poly(ethene) made at 60 d/c and a few atmospheres of pressure with a catalyst

Answer 20

it is rigid and dense

Question 21

why are most polymers not biodegradable

Answer 21

because they are not broken down by microorganisms, so they don’t rot

Question 22

how do you get any oil out of a plant

Answer 22

the plant material is crushed, then the plant material must be crushed between metal plates and the oil is squashed out, oil can also be separated from the crushed plant material by a centrifuge, or solvents can be used. Distillation is then used to refine the oil and get rid of any water solvents or impurities

Question 23

what fuel can be made from vegetable oil

Answer 23

biodiesel

Question 24

oils and fats contain __________ _________ molecules with lots of _________ atoms

Answer 24

oils and fats contain long chain molecules with lots of carbon atoms

Question 25

how many double bonds do monounsaturated fats contain

Answer 25

one double bond

Question 26

how many double bonds do polyunsaturated fats contain

Answer 26

more than one double bond

Question 27

unsaturated vegetable oils are ______ at room temperature

Answer 27

liquid

Question 28

explain how unsaturated oils can be hydrogenated

Answer 28

they can be hardened by reacting them with hydrogen in the presence of a nickel catalyst at about 60 d/c, this is called hydrogenation. The hydrogen reacts with the double bonded carbons and opens out the double bond

Question 29

vegetable oils tend to be _________ while animal fats tend to be _________ ( saturated/unsaturated)

Answer 29

vegetable oils tend to be unsaturated while animal fats tend to be saturated

Question 30

saturated fats are more/less healthy than unsaturated

Answer 30

less healthy, as saturated fats increase the amount of cholesterol in the blood, which can block up the arteries and increase chance of a heart attack)

Question 31

emulsions can be made from_______ and _______

Answer 31

oil and water

Question 32

what is an emulsion

Answer 32

oils don't dissolve in water however you can mix oil with water to get an emulsion. Emulsions are made up of lots of droplets of one liquid suspended in another liquid, you can have an oil in water emulsion (oil droplets suspended in water) or a water in oil emulsion (water droplets suspended in oil)

Question 33

emulsions are ________ than both oil and water (thinner/thicker)

Answer 33

thicker

Question 34

what is an emulsifier

Answer 34

emulsifiers are molecules with one part that's attracted to water and another that attracted to oil or fat. The bit that's attracted to water is called hydrophilic, and the bit that's attracted to oil is called hydrophobic

Question 35

the hydrophilic end of each emulsifier latches onto...

Answer 35

water molecules

Question 36

the hydrophobic end of each emulsifier latches onto...

Answer 36

oil molecules

Question 37

why does the emulsion between oil and water not separate

Answer 37

because when you shake oil and water together with a bit of emulsifier, the oil forms droplets, surrounded by a coating of hydrophilic bit facing outwards. Other oil droplets are repelled by the hydrophilic bit of the emulsifier, while water molecules latch on.

Question 38

what are the pros and cons of emulsifiers

Answer 38

pros emulsifiers stop emulsions from separating out givng hem a longer shell life they allow food companies to produce food that is lower in fat but also still has good texture cons some people are allergic to emulsifiers e.g. egg yolk

Question 39

what does wegener's theory describe

Answer 39

continental drift

Question 40

what are the 4 layers of the earth

Answer 40

inner core, outer core, mantle and crust

Question 41

describe the properties of the crust

Answer 41

it is very thin and is surrounded by atmosphere

Question 42

describe the properties of the mantle

Answer 42

the mantle has all the properties of a solid, except that it can flow very slowly

Question 43

what takes place in the mantle

Answer 43

radioactive decay takes place in the mantle, this producesa lotof heat which causes the mantle to flow in convection currents

Question 44

what is the core made of

Answer 44

iron and nickel

Question 45

how are tectonic plates formed

Answer 45

when the crust and the upper part of the mantle cre cracked into a nuber of large pieces called tectonic plates.

Question 46

what causes tectonic plates to drift

Answer 46

convection currents

Question 47

how are earthquakes caused

Answer 47

they are caused by plates moving suddenly