Organic chemistry Flashcards

1
Q

Explain separating crude oil (3)

A

1) Heat crude oil so it turns into vapour
2) Vapour eneters fractionating column that has a temperature gradient
3) Fractions condense at different levels because they have different boiling points

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2
Q

Crude oil

A

Is a mixture of hydrocarbons with different carbon chain lengths

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3
Q

Hydrocarbons

A

Molecules made up only of carbon and hydrogen atoms

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4
Q

List properties of hydrocarbons change with molecular size

A

1) Intermolecular attraction forces increase
2) Boiling point increases
3) Liquids become less volatile
4) Liquids become viscus
5) Less flammable

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5
Q

less Volatile

A

A liquid evaporates less quickly

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6
Q

more Viscus

A

Liquids take longer to flow , like syrup

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7
Q

How can crude oil be separated? Why?

A

Fractional distillation, as crude oil is a mixture of different hydrocarbons they have different boiling points

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8
Q

Fraction

A

A group of hydrocarbons with similar boiling points

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9
Q

What happens to gas molecules during fractional distillation

A

Condensed back into liquid in the condenser

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10
Q

List all the fractions of crude oil starting with lowest boiling point (7)

A

1) Refinery gasses
2) Gasoline (petrol)
3) Naphtha
4) Kerosine
5) Diesel oil (gas oil)
6) Fuel oil
7) Bitumen

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11
Q

Usage of Refinery gasses

A

Bottled gas

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12
Q

Usage of Gasoline (petrol)

A

Fuel for cars

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13
Q

Usage of Naphtha

A

Making chemicals

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14
Q

Usage of Kerosine

A

Aircraft fuel

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15
Q

Usage of Diesel oil

A

Fuel for cars, lorries, buses

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16
Q

Usage of Fuel oil

A

Fuel for ships, power stations

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17
Q

Usage of Bitumen

A

Roads

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18
Q

List factors which are different in small hydrocarbons to large (4)

A

1) Low boiling point
2) Very volatile
3) Flow easily
4) Ignite easily

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19
Q

Why does viscosity change?

A

More bonds, bigger mass, the forces of attraction between the molecules increases. More force is required to break the bonds

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20
Q

Why does flammability change?

A

More bonds, more energy to break the bonds as there are more forces of attraction between the molecules

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21
Q

Alkanes

A

Saturated hydrocarbon molecule

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22
Q

Saturated

A

An organic compound in which all the bonds are single bonds

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23
Q

What is the generic formula of alkanes

A

CnH2n+2

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24
Q

List factors of alkanes (2)

A

1) All have similar structure

2) They have CH3 at each end of the molecule

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25
Q

What is the difference between alkanes

A

Number of CH2 groups between the two ends

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26
Q

Homologous series (4)

A

A series of organic compounds that….

1) Have the same generic formula
2) Similar chemical reactions
3) Have a trend in physical properties
4) Where each member differs from the next by -CH2- group

27
Q

Generic formula

A

Shows the ratio of atom of each element in a member of homologous series

28
Q

What parts in the name of an alkane made out of? (2)

A

1) Number of carbon atoms in the longest chain

2) Code for alkanes ‘ane’

29
Q

List the code for 1,2,3,4 carbons in the longest chain

A

1) Meth
2) Eth
3) Prop
4) But

30
Q

Molecular formula

A

Shows actual number of atoms of each element in a molecule. No structure is given

31
Q

What is the molecular formula of Propane

A

C3H8

32
Q

What is the molecular formula of Ethane

A

C2H6

33
Q

What is the molecular formula of Butane

A

C4H10

34
Q

Display formula

A

Shows the arrangement of atoms and bonds within a molecule

35
Q

What is the display formula of Propane

A

CH3-CH2-CH3

36
Q

Isomer

A

Compounds that have the same molecular formula, but different display formula

37
Q

Why when alkanes get longer their boiling point increases?

A

As molecules get longer - intermolecular forces increase - more energy is required to break the attraction

38
Q

What need to be done in order to boil a liquid?

A

The forces of attraction have to be broken

39
Q

Give a word equation for complete combustion of methane

A

Methane + oxygen to carbon dioxide + water

40
Q

Give a chemical equation for complete combustion of methane

A

CH4 + 2O2 to CO2 + 2H2O

41
Q

Incomplete combustion

A

In the absence of enough supply of oxygen alkanes may react to form carbon (soot), carbon monoxide and water

42
Q

Equation for combustion methane when black solid is left

A

CH4 + O2 to C + 2H2O

43
Q

Equation for incomplete combustion methane when gas in given out

A

CH4 + 1.5 O2 to CO + 2H20

44
Q

Danger of incomplete combustion? Why?

A

Carbon monoxide is poisonous, as it sticks to the haemoglobin and prevents the uptake of oxygen

45
Q

Alkenes

A

Alkenes are unsaturated hydrocarbons. The carbon atoms are joined by double covalent bonds

46
Q

What is more reactive

A

Alkenes

47
Q

List the products for which ethene is a staring material (3)

A

1) Polymers
2) Antifreeze
3) Paints

48
Q

Cracking

A

Thermal decomposition process, where a big molecule is being split into smaller ones by heating

49
Q

How is industrial cracking carried out?

A

Oil fraction is heated into a gas and passed over a catalyst at high temperature

50
Q

Why is cracking important?

A

Produces alkanes with smaller chain, used for fuel as easier to ignite + produces alkenes which are used to make polymers

51
Q

What catalysts can be used during industrial cracking?

A

1) Silica

2) Alumina

52
Q

Test for unsaturated hydrocarbons

A

Bromine water will go from orange to colourless

53
Q

Why is there a change of colour in the test for unsaturated hydrocarbons?

A

Bromine opens up the double bond

54
Q

Write down a word equation for the test of ethene

A

Ethene + Bromine to dibromoethane

55
Q

Physical properties of alkenes (4)

A

1) Similar to alkenes
2) Smaller alkenes (up to four carbons) are gases at rtp
3) Next dozen a liquids
4) Alkenes burn in oxygen

56
Q

Polymers

A

Long chain molecules made up from joining small molecules called monomers

57
Q

Why polymers take so long to decompose?

A

They have single bonds and bacteria can’t break the links therefore decompose it

58
Q

Problems with polymer waste (3)

A

1) Take very long to decompose
2) Waste uses up valuable land sites
3) Incineration releases lot of useful energy, CO2 and toxic gases

59
Q

What are the solutions to the problems with plastic waste? (2)

A

1) Recycle, reduce disposal problems and amount of crude oil used
2) Biodegradable polymers, possible to include chemicals, that cause the break down more quickly

60
Q

What is the problem with recycling polymers?

A

Different polymers must be separated from each other, difficult and expensive

61
Q

Why plastic windows need no painting?

A

They resist corrosion

62
Q

Why Polymers lead to problems in environment?

A

They are not biodegradable because they are inert

63
Q

Inert

A

Unreactive

64
Q

Not biodegradable

A

Can not be broken down by decomposers