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chemistry > Crude oil and hydrocarbons > Flashcards

Crude oil and hydrocarbons Flashcards

1
Q

what is an organic carbon compound

A

a compound that only contains carbon atoms

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2
Q

what are organic compounds used for

A

run cars, warm homes and generate electricty

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3
Q

formation of crude oil

A

1) tiny ancient sea animals and plants die and are buried in mud
2) layers of rock are then laid on top creating high pressure and temperature in the absence of oxygen
3) this forms fossil fuels, and then more layers of sand and mud fall on top of the fossils squishing them, and turning it into crude oil and natural gas
4) the oil and natural gas are pushed upwards by underground pressure and get stuck under caprock

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4
Q

why isn’t crude oil from the ground useful

A

as it contains many different substances with different boiling points so it would have to be separated into fractions

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5
Q

what is crude oil

A

a dark smelly liquid containing a mixture of carbon compounds

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6
Q

what is a hydrocarbon

A

an organic carbon molecule containing only carbon and hydrogen atoms

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7
Q

what are alkanes

A

saturated hydrocarbons with single-carbon covalent bonds

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8
Q

why cant extra hydrogen atoms be added to alkanes

A

as they have single covalent bonds which means that they contain the maximum amount of hydrogen atoms on each molecule so no more hydrogen atoms can be added

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9
Q

why are alkanes saturated

A

as the have single carbon covalent bonds

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10
Q

formula for alkanes

A

CnH2n+2

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11
Q

how many carbon atoms in methane

A

1

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12
Q

how many carbon atoms in ethane

A

2

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13
Q

how many carbon atoms in propane

A

3

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14
Q

how many carbon atoms in butane

A

4

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15
Q

how many carbon atoms in pentane

A

5

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16
Q

what are fractions

A

a group of hydrocarbons with similar chain lengths

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17
Q

characteristics of short chain hydrocarbons

A
  • low boiling point
  • high flammability
  • low viscosity
  • high volatility
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18
Q

characteristics of long chain

A
  • high boiling point
  • high viscosity
  • low flammability
  • low volatility
19
Q

how is crude oil separated

A
  • its separated into hydrocarbons with similar boiling points called fractions in the process of fractional distillation
20
Q

what does each hydrocarbon fraction contain

A

molecules with a similar number of carbon atoms, this causes the fractions to have different bp due to different sized molecules

21
Q

order from high boiling point to low bp of the different fuels found in a the crude oil distillation tower

A

refinery/ petroleum gas (used as fuel)
gasoline/ petrol (used in car engines)
kerosene (used as aircraft fuel)
diesel oil/ gas oil (fuel for diesel engines and boiler fuel)

22
Q

process of fractional distillation of crude oil

A

1) crude oil is heated
2) the oil is vaporised
3) the vapours move up the fractioning tower
4) the tower is kept very hot at the bottom and much cooler at the top so the temperature decreases going up the tower
5) different vapours condense at different heights and boiling points in the tower to create fractions
6) each fraction contains hydrocarbons of similar-sized molecules with similar boiling points
7) the crude oil is then separated into fractions with smaller hydrocarbons at the top as they have lower boiling points and larger hydrocarbons at the bottom as they have higher boiling points
8) once collected the fractions need more processing before they can be used

23
Q

what is the test for water

A
  • anyhrdous copper sulfate will turn into blue hydrous copper sulfate when water is present (white powder turns into blue crystals)
  • colbalt chloride paper turns from blue to pink when water is present
24
Q

what is produced in complete combustion

A

water and carbon dioxide

25
Q

what is produced in incomplete combustion

A

carbon monoxide

26
Q

why do we crack hydrocarbons

A

as they are made up of large molecules that are thick liquids or solids with high boiling points and are difficult to burn and vapourish so cannot be used as fuels

27
Q

what is cracking

A

breaking down larger useful hydrocarbons into smaller useful ones

28
Q

what happens in a cracker

A

heavy fractions from crude oil is distilled and heated to vaporise the hydrocarbons and the vapour is either passed over a hot catalyst or mixed with steam and heated to a very high temperature

29
Q

what type of reaction is cracking

A

thermal decomposition

30
Q

properties of alkenes

A
  • unsaturated
  • methane cannot be an alkene as it only has 1 carbon atom
  • have double covalent bonds between carbon atoms
31
Q

what is the rule for a cracking formula

A

the total number of carbon and hydrogen atoms in the products has to be equal to the total number of carbon and hydrogen atoms in the reactants

32
Q

process of cracking

A

1) hydrocarbons with large molecules are heated until they turn into there vaporised state
2) hydrocarbons vapours are passed heated catalyst
3) thermal decompose hydrocarbons, until it forms hydrocarbons with small molecules

33
Q

conditions for cracking

A
  • catalyst
  • high temperature and steam
34
Q

why are alkenes useful

A
  • they are used to make polymers
  • they are used as the starting material for other chemicals
  • they are more reactive than alkanes
35
Q

test for alkene

A
  • alkenes turn bromine water from orange to colourless
36
Q

why are alkenes unsaturated

A

as they have two fewer hydrocarbons than the alkane with the same number of carbon atoms

37
Q

what is the homologous series

A

a series of molecules with same functional group, each molecule in a homologous series have an extra carbon atom and two extra carbon atoms

38
Q

what is the alkene functional group

A

the double bond

39
Q

what is a functional group

A

the part of the molecule that determines how it reacts

40
Q

what occurs during hydrogenation (addition reaction)

A

there is an addition of the halogens to alkenes
what do they form
bromine - dibromo
iodine - diodo
chlorine - dichloro

41
Q

what occurs in hydration reaction (addition reactions)

A

there is an addition of water to alkenes

42
Q

conditions for hydration reactions

A
  • the water must be stream
  • the temp must be 300 degrees Celsius
  • the pressure must be 70 atm (atmospheres)
  • phosphoric acid must be used as a catalyst
43
Q

dangers of the cracking experiment

A
  • if the contents in the boiling tube is cooled during the experiment then the water will be sucked back into the boiling tube causing it to crack
44
Q

what to do if a suck back of water is detected in the cracking experiment

A

continue to heat the boiling tube with the hottest part of the flame and remove the boiling tube from the water

chemistry (13 decks)

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