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Chemistry > C9 - Crude oil and fuels > Flashcards

C9 - Crude oil and fuels Flashcards

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1
Q

Where do we find Crude oil ?

A

-Crude oil is found in rocks .

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2
Q

What type of resource is crude oil ? Give the definiton .

A

Crude oil is a finite resource - if we continue to use it it will one day runout .

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3
Q

How is Crude oil formed ?

A

-Crude oil is formed over million of years , from the remains of tiny sea creatures called plankton which were buried in mud .

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4
Q

What is Crude oil a mixture of ?

A

-Crude oil is a mixture of molecules called hydrocarbons .

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5
Q

What are hydrocarbons ?

A

Hydrocrbons are molecules made up of only hyrdogen and carbon atoms only .

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6
Q

Examples of crude oil hydrocarbons .

A

Methane , Ethane , Propane and Butane .

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7
Q

What do scientists call hydrocarbons like methane and ethane ?

A

Alkanes

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8
Q

Formula for Methane and draw it .

A

CH₄

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9
Q

Formula for Ethane and draw it .

A

C₂H₆

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10
Q

Formula for Propane and draw it .

A

C₃H₈

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11
Q

Formula for Butane and draw it .

A

C₄H₁₀

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12
Q

What is a homoglyous series ?

A

A group of compounds with similar properites that differ by CH₂

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13
Q

Scientists say Alkanes are SATURATED , why ?

A

As the carbon atoms are fully bonded to hydrogen atoms in alkanes .

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14
Q

Meaning of Viscosity

A
  • How thick a fluid is .

- Fluids with high viscosity , flow slowly .

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15
Q

As the size of hydrocarbon molecules increases , what happens to the viscosity ?

A

-The molecules become more viscous , very long chain hydrocarbons flow very slwoly - extremely viscous .

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16
Q

Meaning of Flammability ?

A

Tells us how easily a hydrocarbon combusts (burns).

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17
Q

Describe flammability of hydrocarbons .

A
  • Short chain hydrocarbons are extremely flammable .
  • As the size of the hydrocarbon molecules increses , the molecules become less flammable - long chain hydrocarbon are extremely difficult to burn .
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18
Q

Meaning of boiling point ?

A

-The temperature at which a liquid turns into a gas .

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19
Q

Boiling point of short chain hydrocarbons .

A

-Low boiling points
(Methane , Ethane , Propane and Butane are gases at room temperature , as their boiling points are lower than room temperarture .)

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20
Q

What happens to the boiling points as the size of the hydrocarbon molecule increases ?

A

-The boiling point also increases , very long chain hydrocarbons have very high boiling points .

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21
Q

What needs to be done for crude oil to be useful ?

A

-The hydrocarbons in crude oil have to be separated .

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22
Q

How do we seaparate hydrocarbons in crude oil ?

A

Fractional distillations where crude oil is separated into fractions .

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23
Q

What are fractions ?

A
  • Fractions contain hydrocarbons with a similar number of carbon atoms .
  • a group of compounds with simialr boiling points and chian lengths .
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24
Q

Where does fractional distillation take place ?

A

-It takes place in very large colums found in oil refineries .

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25
Q

What is the first stage of fractional distillation of crude oil ?

A

-The crude oil is heated to a veyr high temperature , this causes the crude oil to boil -all the hydrocarbons evaporate and turn into gas .)

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26
Q

What is the second stage of fractional distillation of crude oil ?

A

-The crude oil is now fed into the fractional distillation column . The column is hotter at the bottom and cooler at the top .

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27
Q

Last few steps of fractional distillation of Crude Oil .

A
  1. The hydrocarbon vapours now rise up the column .
  2. Hydrocarbons condedse (turn back into liquid ) when they reach their boiling point .
  3. Liquid fractions then removed .
  4. Remaining hydrocarbons continue moving up the column , there they now condense when they reach their boiling point.
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28
Q

Where is it hto and cold in a fractional distillation collumn ?

A

Hot at the bottom - liquid .

Cool at the top - gas .

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29
Q

Where are long chain hydrocarbons removed in fractional distillation?

A

-Long chain hydrocarbons have a very high boiling point , these hydrocarbons are removed from the bottom of the column .

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30
Q

Where are short chain hydrocarbons removed in fractional distillation ?

A

-Very short chain hydrocarbons have very low boiling points , these do not condense , they re removed at the top of the column as gases .

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31
Q

How are some fractions used

A
  • As fuels - petrol and diesel .

- As feedstock for the petrochemical industry .

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32
Q

What is feedstock ?

A

A chemical used to make other chemicals -e.g detergents .

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33
Q

Meaning of combustion

A

Burning

34
Q

Meaning of Volatility

A

-How easily a substance turns into a gas .

35
Q

Volatitlity of short chain hydrocarbons :

A

-High volatility

36
Q

Volatility of long chain hydrocarbon :

A

-Low Volatility

37
Q

How do Hydrocarbons release energy ?

A

-Hydrocarbons release energy when combusted (burned)

38
Q

What happens during combustion of hydrocarbons ?

A

During combustion , the carbon and hydrogen atoms in the fuel react with oxyegn . The carbon and hydrogen are oxidised .

39
Q

What happens in complete combustion ?

A

-The oxyegn is unlimited , this reaction produces carbondioxide and water .

40
Q

Balance the complete bustion of propane ?

C3H8+02—> What are the products ? balance it .

A

Check sheet .

41
Q

What is incomplete combusion ?

A

-When there is not enoguh oxyegn ot react with the fuel . Products are carbon MONOXIDE (CO) and water .

42
Q

Products of complete combusiton :

A

CO2+H20 (carbon dioxide and water )

43
Q

Products of incomplete combustion :

A

CO+H20 (carbon monoxide and water)

44
Q

What is a homologous series ?

A

-A group of compounds with similar properties that differ by CH2 .

45
Q

When will a liquid condense ?

A

-At its boiling point .

46
Q

Why are smaller alkanes more desirable ?

A

-As smaller alkanes are cleaner when burnt (less smoky than large alkanes . Smaller alkanesare more easier to burn compared to large alkanes .

47
Q

What condition is required for complete combustion to occur ?

A

-Plenty of oxygen for the fuel to react .

48
Q

What condition is required for complete combusiton to occur ?

A

Plenty of oxygen for the fuel to react .

49
Q

What are two key features of alkanes ?

A
  • General formual CnH2n+2

- ( Main one ) Alkanes only have SINGLE covalent bonds between the carbon atoms .

50
Q

Why don’t long chain hydrocarbons make good fuels , what can we do to solve this ?

A
  • They do not as they are not flammable .
  • Issue is that there is a high demand for short chain hydrocarbons , so gotta convert long chain hydrocarbons into shorter ones through a process called cracking .
51
Q

What happens during cracking ?

A

A long chain alkane is broken down (cracked) to produce smaller , more useful moleucles .

52
Q

What are the products of cracking ?

A

-You have the short chain hydrocarbons produced but cracking also produce hydrocarbons known as ALKENES .

53
Q

What are the two ways that can be used for cracking ?

A
  • Catalytic Cracking

- Steam Craking .

54
Q

How does catalytic cracking work ?

A

-In catalytic cracking , we use high temperature and catalysts which speed up the reaction .

55
Q

How does steam cracking work ?

A

-In steam cracking you use , steam and high temperature .

56
Q

What bonds do alkenes have ?

A

-Alkenes have DOUBLE covalent bonds between two carbon atoms (unlike alkanes) .

57
Q

Alkenes are useful molecules , how can they be used ?

A
  • They are used to make chemicals called polymers .

- Alkenes are also used as the starting material for other useful chemicals as well .

58
Q

Reactvity of alkenes .

A

Alkenes are MORE REACTIVE than alkanes . Can use this to test for alkenes .

59
Q

What is the test for alkenes ?

A

-We test for alkenes using bromine water which is orange .
-Of we shake our alkene with bromine water .
-The bromine water turns colourless .
VERY IMPORTANT YOU SAY COLOURLESS NOT CLEAR IN EXAM ..

60
Q

do some balance equations for cracking

A

(check sheet if stuck )

61
Q

What is the MOLECULAR formula of ethene ?

A

C2H4

62
Q

What is the displayed formula , what is the displayed formul of ethene ?

A

The displayed formula shows us all the atoms and the covalent bonds .Check sheet .

63
Q

What is the general formula for alkenes ?

A

C2H2n - If we know the number of carbon atoms (n) , we can calculate the number of hydrogen atoms by X2 the number of carbon atoms .

64
Q

Where can you put double bonds in alkenees ?

A

-In GCSE between any two adjacent carbon atoms .

65
Q

What four alkenes do you need to know ? Write the molecular formula for theemm and the displaed formula .

A

-Ethene
-Propene
-Butene
-Pentene
Check seet for answers .

66
Q

Why do scientists say that alkene molecules are unsaturated ?

A

-As alkenes have two fewer hydrogen atoms than the alkane with same number of carbon atoms .
ETHANE has six hydrogens but ETHENE has four hydrogens , they both have same number of carbon atoms .

67
Q

Why do all alkenes react in a similar way ?

A

As all alkenes have a double bond .

68
Q

What do scientists call the double bond in alkenes ?

A

-The Alkene functional group .

69
Q

What is the meaning of a “functional group”

A

The part of the molecule that determines how it reacts .

-All alkenes have the same fuctional grup (carbon co carbon double bond.)

70
Q

Scientists call molecules like alkenes a homologous series , what does that mean ?

A
  • Molecules of a homologous series has the same fuctionl group and the same formula and difer by CH2
  • Each molecule in the homologouse series has an extra carbona tom and two extra hydrogen atoms /
71
Q

What are the products of the combustion of alkenes ?

A

-Produce carbondioxide and ater like alkanes .
-However , incomplete combustion of an alkene also produces unburnt carbon paerixles , this is because of incomplete combstion .
As a result , alkenes burn in air with a smoky flame .

72
Q

What are the requirements of hydrogenation ?

A
  • This reaction requires a temperature of around 150 degrees .
  • Also requires a nickel catlayst to speed up the reaction .
73
Q

How are the hydrogen atoms added in hydrogenation ?

A
  • The two hydrogen atoms are added across the double bond .

- The carbon to carbon double bond is converrted ino a carbon to carbon single bond .

74
Q

What happened to the hydrogenaiton reactionn ont he page .

So what does reacitng an alkene with hydrogen produce ?

A
  • It converted ethene into the alkane ethane .

- Reacting an alkene with hydrogen produces an alkane .

75
Q

-What fractions of crude oil are usually cracked

A

Naptha

76
Q

-Why are they cracked

A

-To rpoduce moe useful and shorter chain alkanes .

77
Q

-What type of reaction is cracking ?

A

-Thermal decompostion - when a compound breaks down when heated .

78
Q

What are the two products formed in cracking ?

A
  • Short chain alkane

- alkene .

79
Q

meaning of combustion (burning)

A

-The reaction of something with oxygen .

80
Q

Give for useful products from fractional distillatio .

A
  • Solvents
  • Lubricating oils
  • Fuels
  • Detergents

Chemistry (20 decks)

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