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edexcel a level chemistry > deck_14406789 > Flashcards

deck_14406789 Flashcards

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1
Q

What is structural formula?

A

Shows the arrangement of atoms carbon by carbon with the attached hydrogens and functional groups

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2
Q

What is skeletal formula?

A

Shows the bonds of the carbon skeleton only, with any functional groups

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3
Q

What is displayed formula?

A

Shows how all the atoms are arranged, and the bonds between them, drawn out

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4
Q

What is addition?

A

Joining two or more molecules together to form a larger molecule

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5
Q

What is polymerisation?

A

Joining together lots of simple molecules to form a large one

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6
Q

What is elimination?

A

When a small group of atoms breaks away from a larger molecule

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7
Q

What is substitution?

A

When one species is replaced by another

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8
Q

What is hydrolysis?

A

Splitting a molecule into two molecules by adding H+ and OH- derived from water

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9
Q

What is a species?

A

An atom, an ion, a radical or a molecule

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10
Q

What is a nucleophile?

A

An electron pair donor, often negatively charged ions or species with a lone pair

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11
Q

What are nucelophiles attracted to?

A

A delta positive Carbon

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12
Q

What is an electrophile?

A

Electron pair acceptors, positively charged ions attracted to electron rich areas

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13
Q

What is a radical?

A

A species with an unpaired electron

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14
Q

What are structural isomers?

A

The molecular formula is the same but the structural formula is different

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15
Q

What are chain isomers?

A

The carbon chain is arranaged differently

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16
Q

What are positional isomers?

A

Where the functional group is attached to a different carbon

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17
Q

What are functional group isomers?

A

The isomers have different functional groups

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18
Q

Can atoms rotate around a C-C bond?

A

Yes

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19
Q

What type of hydrocarbons are alkanes?

A

Saturated

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20
Q

What are the two types of fission?

A

Homolytic and heterolytic

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21
Q

What is heterolytic fission?

A

The bond breaks unevenly with one of the bonded atoms recieving both electons from the bonded pair

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22
Q

What is homolytic fission?

A

The bond breaks evenly and each bonding atom receives one electron from the pair

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23
Q

What does heterolytic fission produce?

A

Two ions, one + and one -

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24
Q

What does homolytic fission produce?

A

Two radicals

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25
Q

In what reactions do alkanes react with halogens?

A

Free radical substitution

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26
Q

What are the steps of free radical substitution?

A

InitiationPropagationTermination

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27
Q

What is photodissociation?

A

When radicals are produced by sunlight in Cl-Cl bonds

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28
Q

What happens in propagation reactions?

A

Radicals are created and used up

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29
Q

What can happen in propagation between methan and a chlorine radical?

A

Cl. + CH4 ——> CH3. + HCl| .CH3 + Cl2 ——> CH3Cl + Cl.

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30
Q

What happens in termination reactions?

A

Radicals are used up as they react with each other

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31
Q

What is the main problem with free radical substitution?

A

A mixture of products is created

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32
Q

What is crude oil mainly made up of?

A

Alkanes

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33
Q

What temperature is used to vaporise crude oil?

A

350 degrees C

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34
Q

Why don’t the largest hydrocarbons vaporise?

A

Their boiling points are too high

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35
Q

What happens to the vapour as it moves up the fractionating column?

A

It cools, and each fraction condenses at a different temperature

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36
Q

What happens to the hydrocarbons with the lowest boiling points?

A

The don’t condense, they’re drawn out as gases at the top of the column

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37
Q

How can the heaviest fractions be used?

A

They can be ‘cracked’ to form smaller molecules

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38
Q

What are the two types of cracking?

A

Thermal and catalytic

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39
Q

What are the conditions of thermal cracking?

A

1000 degrees C and high pressure (70 atm)

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40
Q

What does thermal cracking produce?

A

Alkenes

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41
Q

What is the catalyst in catalytic cracking?

A

Zeolite (hydrated aluminosilicate)

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42
Q

What does catalytic cracking produce?

A

Aromatic hydrocarbons and motor fuels

43
Q

Why is catalytic cracking more beneficial?

A

It cuts costs, because lower pressure and temperature can be used and the reaction is sped up by the catalyst

44
Q

What can alkanes be reformed into?

A

Cycloalkanes and aromatic hydrocarbons

45
Q

What is knocking?

A

Where alkanes explode of their own accord when the fuel/air mixture in the engine is compressed

46
Q

What are the most likely hydrocarbons to cause knocking?

A

Straight chain ones

47
Q

What catalysts are used for reforming?

A

Platinum on aluminium oxide

48
Q

What state do fuels have to be in to undergo combustion reactions?

A

Gaseous

49
Q

Why do larger alkanes produce more energy per mole?

A

They have more bonds to break

50
Q

What are the issues with carbon monoxide?

A

Carbon monoxide is better at bonding with haemoglobin so less oxygen is carried around the blood stream, leading to oxygen deprivation, and this can be fatal

51
Q

What are the issues with SO2 and NOx?

A

Acid rain can be caused by the burning of fuels that contain sulfur, as the sulfur dioxide can be converted to sulfuric acid.Oxides of Nitrogen can also cause acid rain as they are converted into nitric acid

52
Q

What is the main issue with fossil fuels?

A

They are non-renewable

53
Q

What biofuels are available?

A

BioethanolBiodieselBiogas

54
Q

How is bioethanol made?

A

By the fermentation of sugar from crops sch as maize

55
Q

How is diodiesel made?

A

By refining renewable fats and oils such as vegetable oils

56
Q

How is biogas made?

A

Produced by the breakdown of organic waste matter

57
Q

Why are biofuels classed as carbon neutral?

A

Because although they release CO2 when burnt, the plants took in CO2 as they grew.

58
Q

What are the problems with biofuels?

A

Petrol car engines have to be modified to use the fuel and land used to grow the crops then can’t be used to grow food, an issue in developing countries

59
Q

What are sigma bonds?

A

Single covalent bonds

60
Q

When is a sigma bond formed?

A

When two orbitals overlap in a straight line, giving the highest possible electron density between two positive nuclei

61
Q

What does the high electron density between the nuclei mean for sigma bonds?

A

That there is strong electrostatic attraction and so sigma bonds are the strongest

62
Q

What is a pi bond?

A

The second part of a double bond, along with a sigma bond

63
Q

How are pi bonds formed?

A

When two lobes of two orbitals overlap sideways - one above and one below the molecular axis

64
Q

What is the electron density in a pi bond like?

A

Spread out, above and below the nuclei so the electrostatic attraction is weaker and they are more easily broken

65
Q

How do strengths of double and single bonds compare?

A

A double bond is less than twice as strong as a single bond

66
Q

Can double bonds rotate?

A

No

67
Q

Why can double bonds rotate?

A

Because the p-orbitals overlap in pi bonds

68
Q

What are Z-isomers?

A

When the same groups are either both above or both below the bond

69
Q

What are E-isomers?

A

When the same groups are on opposite sides, one above and one below the double bond

70
Q

How does E/Z isomerism work when all the groups are different?

A

The atoms with the larger atomic numbers are given priority

71
Q

What are cis isomers?

A

When the groups are on the same side of the double bond, eg both above or both below

72
Q

What are trans isomers?

A

When the groups are on different sides of the double bond, eg one above and one below

73
Q

When is E/Z isomerism used?

A

When there are two high-priority groups

74
Q

When is cis/trans isomerism used?

A

When there are two groups the same, no matter of their priority

75
Q

How are dihalogenoalkanes made?

A

By reacting halogens with alkenes

76
Q

How are alcohols made from alkenes?

A

Through steam hydration

77
Q

How are diols made from alkenes?

A

Oxidation by acidified potassium dichromate

78
Q

How many products are formed when hydrogen halides are added to unsymmetrical alkenes?

A

Two

79
Q

What is Markownikoff’s rule?

A

The major product from addition of hydrogen halides to unsymmetrical alkenes is the one where the hydrogen adds to the carbon with the most hydrogens already attached (ie ones with alkyl groups)

80
Q

What do alkenes join up to form?

A

Addition polymers

81
Q

What are the different methods for disposing of polymers?

A

Waste plastics can be buried, reused or burned

82
Q

When is landfill used to dispose of plastics?

A

When they are difficult to separate from other wasteNot are not in sufficient quantities to make separation worthwhileToo difficult to technically recycle

83
Q

How can waste plastics be reused?

A

They can be melted and remoulded| They can be cracked into monomers and resued again

84
Q

What can the burning of waste plastics be used for?

A

Generating electricity

85
Q

How can making polymers be made sustainable?

A

Use reactant molecules that are as safe and environmentally friendly as possibleUse as few other materials, eg solvents, as possibleUse renewable raw materialsKeep energy use to a minimum

86
Q

What is a primary halogenoalkane?

A

One alkyl group attached to Carbon with X bonded

87
Q

What is a tertiary halogenoalkane?

A

Three alkyl groups attached to Carbon with X bonded

88
Q

What can halogenoalkanes be hydrolysed to form?

A

Alcohols

89
Q

Why are iodoalkanes hydrolysed the fastest?

A

Iodoalkanes have the longest, weakest bonds, which are easiest to break

90
Q

How can the rate of hydrolysis of halogenoalkanes be compared?

A

Mix halogenoalkane with ethanolAdd silver nitrateTime how long it take for precipitate to form

91
Q

Halogenoalkane + Aqueous KOH —->

A

Alcohol + KX

92
Q

Hlaogenoalkane + CN- —->

A

Nitrile + X-

93
Q

Halogenoalkane + NH3 —->

A

Amine + NH4+

94
Q

Halogenoalkane + KOH + Ethanol + reflux —->

A

Alkene + H2O + KBr

95
Q

Alcohol + PCl5 —->

A

Chloroalkane + HCl + POCl3

96
Q

Alcohol + HBr —->

A

Bromoalkane + H2O

97
Q

Alcohol + PI3 —->

A

Iodoalkane + H3PO3

98
Q

Alcohol + acid catalyst + heat —->

A

Alkene + water

99
Q

What is the simplest way to oxidise alcohols?

A

Burn them

100
Q

What can primary alcohols be oxidised to?

A

Aldehydes, then carboxylic acids

101
Q

What can secondary alcohols be oxidised to?

A

Ketones

102
Q

What can tertiary alcohols be oxidised to?

A

Nothing - they can’t be oxidised

103
Q

What is used to oxidise alcohols?

A

Acidified potassium dichromate

edexcel a level chemistry (2 decks)

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