fractional distillation and cracking Flashcards

(36 cards)

1
Q

what is crude oil

A

fossil fuel made from remains of ancient biomass

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2
Q

what are the first 4 alkenes

A

methane
ethane
propane
butane

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3
Q

formula to work out alkene

A

Cn H2n+2

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4
Q

hydrocarbon

A

compound only with hydrogen and carbon

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5
Q

what is the use of petrol

A

fuel for cars

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6
Q

what is the use of naphtha

A

used to manufacture chemicals

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7
Q

what is the use of bitumen

A

used for laying roads

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8
Q

what is the use of kerosene

A

fuel for aircrafts

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9
Q

what is the use for diesel

A

fuel for cars, vans and lorries

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10
Q

what is fractional distillation

A

separate components with different condensing temperatures in a mixture

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11
Q

where does fractional distillation take place

A

fractionating column

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12
Q

what is cracking

A

breaking down large molecules in to smaller more useful ones

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13
Q

where does cracking take place

A

oil refinery in steel vessels

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14
Q

how does cracking work

A

heavy fractional of distilled crude oil is heated to vaporise hydrocarbons

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15
Q

what happens to the vapour in cracking

A

passed over a hit catalyst
mixed with steam and heated ti a very high temp

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16
Q

what is cracking an example of

A

thermal decomposition

17
Q

why is cracking so important

A

to meet demands for fuels

18
Q

how can large hydrocarbon molecules be cracked in an oil refinery

A

hydrocarbon vapours passed over a hot catalyst

19
Q

unsaturated hydrocarbon

A

hydrocarbon containing at least 1 C=C double bond

20
Q

type of bonding in hydrocarbons

21
Q

what properties would you expect from a hydrocarbon

A

low boiling point due to covalent bond (molecules)

22
Q

How many bonds does each hydrogen atom need to make?

23
Q

How many bonds does each carbon atom need to make?

24
Q

why are hydrocarbons good fuels?

A

with OXYGEN exothermically producing CO2 and steam

25
why are hydrocarbons better fuels that wood /coal?
don’t make ash so there is no need to clean out the combustion chamber
26
what problems are associated with using hydrocarbons as fuel?
CO2 is a greenhouse gas climate change
27
how many joules of energy does 1 mole go petrol release (assuming complete combustion)
6770kJ
28
define a FUEL
substance that releases energy when burnt
29
properties of alkanes
saturated no double bonds
30
properties of short chain hydrocarbons
low BP and MP very flammable low viscosity
31
word equation for complete combustion
Fuel +oxygen - >carbon dioxide + water
32
when are alkenes formed
when we crack large alkanes
33
uses of alkenes
used to make polymers and plastic
34
do we use alkenes for fuel
no
35
test for alkenes
bromine water positive test becomes colourless negative test stays orange
36
how to draw alkenes
1 double bond between the carbons