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OCR A Level Chemistry > Topic 4 - Core Organic Chemistry > Flashcards

Topic 4 - Core Organic Chemistry Flashcards

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1
Q

What do all organic compounds contain?

A

Carbon

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2
Q

How many known carbon compounds are there?

A

10 million

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3
Q

How many new carbon compounds are discovered each year?

A

300,000

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4
Q

What does organic mean?

A

living

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5
Q

What do hydrocarbons contain?

A

carbon and hydrogen atoms only

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6
Q

What is the bonding like in hydrocarbons? What does this mean?

A

covalent so bonding between molecules is weak

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7
Q

Alkane general formula

A

CnH2n+2

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8
Q

Are Alkanes saturated or not?

A

Saturated

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9
Q

What does saturated mean?

A

no C=C carbon double bonds

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10
Q

Alkene general formula

A

CnH2n

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11
Q

What does unsaturated mean?

A

contains one or more C=C carbon double bonds

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12
Q

Are Alkenes saturated or unsaturated?

A

unsaturated

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13
Q

Number of carbons and formula of methane

A

1 C1H4

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14
Q

Number of carbons and formula of ethane

A

2 C2H6

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15
Q

Number of carbons and formula of propane

A

3 C3H8

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16
Q

Number of carbons and formula of butane

A

4 C4H10

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17
Q

Number of carbons and formula of pentane

A

5 C5H12

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18
Q

Number of carbons and formula of hexane

A

6 C6H14

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19
Q

Number of carbons and formula of heptane

A

7 C7H16

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20
Q

Number of carbons and formula of octane

A

8 C8H18

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21
Q

Number of carbons and formula of nonane

A

9 C9H20

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22
Q

Number of carbons and formula of decane

A

10 C10H22

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23
Q

Define homologous series

A

A homologous series is a series of organic compounds having the same functional group but with each successive member differing by CH2-

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24
Q

Define functional group

A

A functional group is a group of atoms responsible for the characteristic reactions of a compound

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25
Q

What is the carboxyl group and where is it found?

A

COOH is the carboxyl group, found in carboxylic acids

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26
Q

What do functional groups determine?

A

the pattern of reactivity

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27
Q

What does the carbon chain length determine?

A

physical properties such as melting/boiling points

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28
Q

What are aliphatic alkanes like?

A

Carbon atoms arranged in chains (branched and unbranched)

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29
Q

What are alicyclic alkanes like?

A

Carbon atoms arranged in ring structures

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30
Q

What are aromatic alkanes like?

A

carbon atoms using benzene structure

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31
Q

What is the alcohol group?

A

OH

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32
Q

How else can C2H5 be written?

A

CH3CH2

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33
Q

How else can C3H7 be written?

A

CH3CH2CH2

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34
Q

What is R?

A

The alkyl group (the alkane subtract a H)

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35
Q

Haloalkane functional group

A
  • Cl
  • Br
  • I
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36
Q

Aldehyde functional group

A

-CHO

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37
Q

Ketone functional group

A

-C(CO)C-

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38
Q

Carboxylic acid functional group

A

-COOH

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39
Q

Ester functional group

A

-COO

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40
Q

What is the stem?

A

This is the number of carbon atoms in the longest chain bearing the functional group

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41
Q

What is the prefix?

A

This shows the position and identity of any side chain substituents

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42
Q

What is the suffix?

A

This shows the functional group is present

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43
Q

How to get stem name?

A

Take ‘ane’ off the alkane name

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44
Q

Alkene suffix

A

-ene

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45
Q

Alkyne suffix

A

-yne

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46
Q

Carboxylic acid suffix

A

-oic acid

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47
Q

Alcholol suffix

A

-ol

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48
Q

Aldehyde suffix

A

-al

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49
Q

Ketone suffix

A

-one

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50
Q

Acyl chloride suffix

A

-oyl chloride

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51
Q

amide suffix

A

-amide

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52
Q

CH3 - prefix

A

methyl

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53
Q

Cl- prefix

A

Chloro

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54
Q

Br- prefix

A

Bromo

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55
Q

I- prefix

A

Iodo

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56
Q

OH- prefix

A

Hydroxy

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57
Q

C2H5- prefix

A

ethyl

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58
Q

C3H7- prefix

A

propyl

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59
Q

C4H9- prefix

A

butyl

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60
Q

RULES FOR NAMING (6)

A
  1. number the longest carbon chain from one end to give the lowest numbers to the side chains
  2. Sidechain names appear in alphabetical order
  3. Each side chain is given its own number
  4. If identical side-chains appear more than once, prefix with di, tri, tetra, penta, hexa etc
  5. Numbers are seperated from names by hyphen (2-methylheptane)
  6. Numbers are seperated from numbers by a comma (2,3-dimethylbutane)
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61
Q

Define molecular formula

A

tells us the actual number and type of atom in a compound

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62
Q

Define empirical formula

A

this is the simplest whole number ratio of atoms in compound

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63
Q

Give the general, structural, molecular and empirical formula of butane (allowed to use paper to work out)

A

General formula CnH2n+2
CH3 CH2 CH2 CH3 is the structural formula
Molecular formula is C4H10
Empirical formula is C2H5

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64
Q

What do skeletal formulas show?

A

These show carbon chains and major functional groups only, H’s are not shown

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65
Q

In skeletal formulas where are the carbons?

A

At the end of lines

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66
Q

Define structural isomer

A

Structural isomers are compounds with the same molecular formula but different structural formulae.

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67
Q

Give an example of a structural isomer

A

C3H10 can be shown in two ways:
.CH3CH2CH2CH3
.CH3CH(CH3)CH3

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68
Q

How can isomers with functional groups form?

A

In compounds containing a functional group, the functional group can be at different positions along the carbon chain.

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69
Q

Can different functional groups have the same molecule formula? example.

A

Sometimes two molecules containing different functional groups have the same molecular formula. Aldehydes and Ketones with the same number of carbon atoms have the same molecular formulae. The molecular formula C3H6O could represent propanal or propanone.

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70
Q

Can isomers change smell?

A

yes

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71
Q

Give an example of isomers that change smell?

A

Linalool and geraniol are isomers and have similar chemical properties that are used in perfumes.
Linalool smells of lavender and geraniol of roses.

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72
Q

What two ways can covalent bonds be broken?

A

homolytic fission or heterolytic fission.

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73
Q

What is homolytic fission?

A

When covalent bonds break by homolytic fission, each of the bonded atoms take one of the shared pairs of electrons from the bond.
.Each atoms now has a single unpaired electron

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74
Q

What is a radical?

A

.An atom or groups of atoms with an unpaired electron

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75
Q

What is herolytic fission?

A

When a covalent bond breaks by heterolytic fission, one of the bonded atoms takes both of the electrons from the bond
.The atom that takes both electrons becomes a negative ion
.The atom that does not take the electron becomes a positive ion

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76
Q

What is the reaction mechanisn?

A

information about how the reaction takes place

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77
Q

In a reaction mechanism, what do curly arrows show?

A

the movement of electron pairs when bonds are being broken or made.

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78
Q

In a reaction mechanism, what do hald-headed curly arrows show?

A

show the movement of a single unpaired electron in mechanisms involving mechanisms.

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79
Q

What are the 3 types of reactions?

A

Addition, subsituton and elminiation

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80
Q

What happens in an addition reaction?

A

In an addition reaction, two reactants join together to form one product.

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81
Q

What happens in a substitution reaction?

A

In a substitution reaction, an atom or group of atoms is replaced by a different atom or groups of atoms.

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82
Q

What happens in an elimination reaction?

A

An elimination reaction involves the removal of a small molecule from a larger one. In an elimination reaction, one reactant molecule forms two products. Usually through a catalyst.

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83
Q

Define structural isomers

A

Molecules with the same molecular formula but a different structural formula

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84
Q

What do double bonds not do?

A

Rotate

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85
Q

Define stereoisomers

A

These are molecules with the same molecular formula, the same structural formula but a different spatial arrangement of atoms

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86
Q

For geometric isomerism what must a molecule have?

A

. A c=c double bond (non rotating)

. Each c must have 2 different groups attached

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87
Q

In geometric isomerism if it’s opposite it’s an _ isomer

A

E

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88
Q

In geometric isomerism if it’s together it’s a _ isomer

A

Z

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89
Q

In terms of isomers what does trans mean? How to remember?

A

Trans, across the isomer, the E isomer, think trans-Atlantic

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90
Q

In terms of isomers what does cis mean? How to remember?

A

Cis, adjacent isomer, the Z isomer, think stays the same

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91
Q

What is the cahn-ingold-prelog nomenclature?

A

.A more up to date system gives priority to groups based on their atomic number (high number = high priority) when thinking where elements go on isomers

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92
Q

Why is a cation called such?

A

it is positive and so goes to the cathode

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93
Q

Why is an anion called such?

A

it is negative and so goes to the anode

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94
Q

What is an electrophile?

A

A positive species which is able to accept a pair of electrons (means electron loving)

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95
Q

What is a nucleophile?

A

A negative species which is able to donate a pair of electrons (means nucleus loving)

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96
Q

Alkanes are saturated, what does this mean?

A

single bonds between carbons only

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97
Q

Alkane general formula

A

CnH2n+2

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98
Q

What allowed crude oil to remain for millions of years?

A

The are among the most stable organic compounds – lack of reactivity

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99
Q

What are alkanes components of?

A

oil and gas

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100
Q

What are alkanes mainly used as?

A

fuels to release energy

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101
Q

What leads to the formation of sigma bonds?

A

The overlap of orbitals directly between the bonding atoms leads to the formation of sigma bonds (σ-bonds).

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102
Q

What happens around sigma bonds?

A

Free rotation

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103
Q

Describe the relationship between boiling points straight alkanes

A

As the carbon chain increases the boiling point increases

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104
Q

Explain the relationship between boiling points straight alkanes

A

As the carbon chain length increases the surface are of interaction between molecules increases and thus the size of the London forces also increases (due to the greater number of electrons and thus size of temporary and induced dipoles), hence more energy needs to be provided to disrupt these stronger London forces, leading to a higher boiling point.

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105
Q

Describe the relationship between boiling points and branched alkanes

A

As the amount of branching increases, the boiling point goes down

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106
Q

Explain the relationship between boiling points and branched alkanes

A

As the amount of branching increases the surface area of interaction between molecules decreases and thus size of the London forces also decreases, hence less energy needs to be provided to disrupt these weaker London forces, leading to a lower boiling point.

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107
Q

Why are alkanes quite unreactive?

A

.C-C and C-H bonds are strong (have high bond enthalpy)
.C-C bonds are non-polar
.C-H are virtually non-polar

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108
Q

What happens with the complete combustion with alkanes?

A

In a plentiful supply of oxygen, combustion of alkanes will always lead to the production of CO2 and water.

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109
Q

What happens with the incomplete combustion with alkanes?

A

In a limited supply of oxygen, combustion of alkanes will lead to the production of CO (carbon monoxide) and water.

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110
Q

What does a covalent bond in a diatomic halogen molecule need to be broken?

A

UV light

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111
Q

What are the mechanistic steps in homolytic fission?

A

The initiation step, the propagation step and the termination step

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112
Q

What is the termination phase in homolytic fission?

A

addition of two three radicals

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113
Q

General mechanism of homolytic fission

A

X2  UV light  X● + X●
CaHb + X●  CaHb-1 + HX
CaHb-1● + X2  CaHb-1X + X●
CaHb-1● + X●  CaHb-1X

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114
Q

Evaluate the substitution of alkanes

A

.Further substitution can occur with more H’s being replaced by additional bromines
.Additionally substitution can occur at different points in a carbon chain

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115
Q

Alkene general formula

A

CnH2n

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116
Q

Does an alkene exist with 1 carbon?

A

no

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117
Q

Are alkenes saturated or unsaturated?

A

Unsaturated

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118
Q

What is the test for alkenes?

A

bromine water is decolourised (orange to colourless)

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119
Q

What is a pi bond?

A

these are formed by the sideways overlap of the two adjacent p orbitals

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120
Q

Chemical formula of limonene

A

C10H16

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121
Q

What is limonene responsible for?

A

The smell and flavour of lemons and oranges

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122
Q

What happens in an alkene addition reaction?

A

The double bond opens up and allows two atoms to join to it

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123
Q

What happens in a hydrogenation of an alkene?

A

Addition reaction with hydrogen

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124
Q

Conditions for hydrogenation of alkene

A

nickel catalyst and 150’C

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125
Q

Why does the Z isomer have a lower boiling point?

A

It cant pack as closely together

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126
Q

What happens with hydration of alkenes?

A

.Alkenes will react with steam, H2O, in the presence of phosphoric acid, H3PO4, to produce alcohols

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127
Q

What does bromine water test for?

A

Unsaturation

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128
Q

Why is HBr polar?

A

Br is more electronegative

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129
Q

Explain how electrophilic addition works using HBr as an example

A

HBr is polar due to electronegative Br
The pi electrons attracted towards the Hs+, i.e. pi bond breaks
Hs+ acts as an electrophile (accepts a pair of electrons)
H-Br bond breaks via heterolytic fission

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130
Q

What is an electrophile?

A

‘electron loving’, able to accept a pair of electrons

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131
Q

What is a nucleophile?

A

‘nucleus loving’, able to donate a pair of electrons

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132
Q

Why is Br2 non-polar?

A

Both Br atoms have the same electronegativity

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133
Q

How does Br2 react with an alkene?

A

Bromine is none polar due to each atom having the same electronegativity
But as bromine approaches the pi bond on the alkene, it repels the electrons in the bond and pushes them away, giving the bromine atoms slight charges
The pi electrons induce a dipole in the non-polar Br2 molecule as it approaches the bond
This means electrophilic addition can ensue

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134
Q

In electrophilic addition, in the stage between the adition of the electrophile and the addition of the other atom, what is the alkene called? Why?

A

A carbocation (or carbonium ion) as it has a positive charge

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135
Q

What forms of carbocations are there?

A

Primary, secondary and tertiary

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136
Q

How do +I affects increase stability?

A

Carbon centres have a positive inductive effect (+I). This pushes electron density towards the C+ and helps to stabilise it.

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137
Q

The more +I effects,

A

the more stable the carbonium ion

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138
Q

The more stable ions are,

A

more favourable

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139
Q

Which product of electrophillic thing is more favourable?

A

Major product

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140
Q

What is markownikoffs rule?

A

The major product is produced when the negative part of the molecule joins to the carbon with the least number of attached H (hydrogen) atoms within the double bond.

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141
Q

What is the order of carbonium ion stability? Why?

A

Primary carbonium ions are less stable than secondary, which are less stable than tertiary, because:

  • Primary = 1 x +I
  • Secondary = 2 x +I
  • Tertiary = 3 x +I
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142
Q

Draw the electrophillic mechanism for HCl and CH3CH=CH2

A

Check notes from 29.1.20

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143
Q

When drawing polymer reactions, what does the ‘n’ mean?

A

lots

144
Q

When drawing polymer reactions, where do the brackets go?

A

Around the monomer in the polymer, over the bonds on the edge

145
Q

When is an addition polymer formed?

A

when lots of small alkene monomers join together to form a long chain molecule called a polymer (and no other product).

146
Q

What is polyethene used in?

A

carier bags

147
Q

What is polystyrene used in?

A

used in cups, packaging and cutlery

148
Q

What is polytetrafluorine (PTFE) used for?

A

Non-stick coatings

149
Q

Scientific name for polystyrene

A

polyphenylethene

150
Q

Example of PTFE

A

teflon

151
Q

Describe structure and resultant properties of high density poly(ethane) (HDPE)

A

straight polymer chains, chains packed tightly together, strong forces between chains, strong and tough material, high melting point

152
Q

Describe structure and resultant properties of low density poly(ethane) (LDPE)

A

branched polymer chains, chains cant pack close together, weak forces between chains, weak but flexible material, low melting point

153
Q

What does the type of polymer depend on?

A

the temperature and catalyst used during production

154
Q

Pros of polymers we use

A
  • Readily available
  • Cheap to use
  • More convenient than alternatives (glass, metal, paper and cardboard)
  • Lack of reactivity makes them suitable for storing food
155
Q

Cons of polymer we use

A
  • Non-biodegradable

- Growing amount of waste has environmental effects, for example killing marine life

156
Q

How does recycling polymers reduce their environmental impact?

A

by conserving finite fossil fuels as well as decreasing the amount of waste going into landfill.

157
Q

How are polymers recycled?

A

First the polymers have to be sorted, as if they are mixed then the product is rendered useless, and then they are chopped into flakes, washed, dried and melted. The recycled polymer is cut into pellets and used by manufacturers to make new products.

158
Q

Why is PVC recycling hazardous?

A

The disposal and recycling of PVC is hazardous due to the high chlorine content and the range of additives present in the polymer. Dumping PVC in landfill is not sustainable and, when burnt, releases hydrogen and chlorine (a poisonous gas), and other pollutant like toxic dioxins.

159
Q

How is PVC recycled?

A

Solvents dissolve the polymer, high-grade PVC is then recovered by precipitation from the solvent, and the solvent is used again.

160
Q

Why are some polymers difficult to recycle?

A

as they are from petroleum or natural gas, they have a high stored energy value

161
Q

What happens to some waste polymers that are difficult to recycle?

A

Waste polymers can be incinerated to produce heat, which generates steam to turn a turbine to produce electricity

162
Q

What is feedstock recycling?

A

.Feedstock recycling describes the chemical and thermal processes that can reclaim monomers, gases, or oil from waste polymers

163
Q

What do the products of feedstock recycling resemble?

A

those produced from crude oil in refineries

164
Q

What can products of feedstock recycling be used as?

A

raw materials for the production of new polymers

165
Q

Name an advantage of feedstock recycling

A

that it can handle unsorted and unwashed polymers

166
Q

What are bioplastics produced from?

A

Bioplastics produced from plant starch, cellulose, plant oils, and proteins

167
Q

Are bioplastics renewable and sustainable?

A

Yes

168
Q

Why are bioplastics good?

A

not only protects our environment but also conserves natural resources

169
Q

How are biodegradebale polymers broken down?

A

.Biodegradable polymers are broken down by microorganisms into water, carbon dioxide and, biological compounds

170
Q

What do biodegradaeble polymers usually contain?

A

These polymers are usually made of starch or cellulose, or contain additives that alter the structure of traditional polymers so that microorganisms can break them down

171
Q

When compostable polymers degrade, they leave no what?

A

No visible or toxic residues

172
Q

Why are bin liners made from plant starch good?

A

can be used as bin liners for food waste, so the food and bin liner can be composted together

173
Q

What is replacing polystyrene?

A

Compostable plates, cups and food trays made from sugar cane fibre

174
Q

What are photodegradable polymers based on and when are they used?

A

Where plant based polymers aren’t available, photodegradable oil-based ones are being developed

175
Q

How are photodegrable polymers broken down?

A

These polymers contain bonds that are weakened by absorbing light to start the degradation. Alternatively, light absorbing additives are used

176
Q

Alcohol general formula

A

CnH2n+1OH

177
Q

Name first 6 alcohols

A

methanol, ethanol, propanol, butanol, pentanol, hexanol

178
Q

Name the isomers of butanol

A

Butan-1-ol
Butan-2-ol
2-methylpropan-1-ol
2-methylpropan-2-ol

179
Q

Describe the process of fermentation

A
  1. Extract sugar (glucose) from crops
  2. Add yeast to glucose (enzymes in yeast act as a catalyst)
  3. Fermentation occurs
180
Q

What type of process if fermentation?

A

Batch process

181
Q

What is the optimum temperature for fermentation?

A

30-40’C

182
Q

Fermentation equation

A

C6H12O6 –> 2CH3CH2OH + 2CO2

183
Q

Advantages of fermentation

A

.Sugars are a renewable resource
.Batch process, so the equipment is cheap
.More carbon neutral (bio fuel)

184
Q

Disadvantages of fermentation

A

.Very slow
.Very impure - needs further processing, fractional distillation, which takes time and money
.Batch process, so high labour costs

185
Q

Describe the hydration of ethene to form ethanol

A

.Extract crude oil from the ground
.Oil refinery - fractional distillation then cracking to get ethene
.Hydration (addition of steam)

186
Q

Is the hydration of ethene a continuous process?

A

yes

187
Q

Needed environment for hydration of ethene

A

.Phosphoric acid catalyst

.High temperature and pressure

188
Q

Equation for hydration of ethene

A

C2H4 + H2O –> CH3CH2OH

189
Q

Advantages of hydration of ethene

A

.Fast reaction
.Pure product
.95% yield (initially 5% but can recycle unreacted ethene)
.Continuous (cheaper man power)

190
Q

Disadvantages of hydration of ethene

A

.High technology equipment needed, expensive initial cost
.High energy costs for high pressure
.Ethene is non-renewable

191
Q

How do alcohols compare, when looking at physical properties, to the corresponding alkanes?

A

alcohols are less volatile, have higher melting points and greater water solubility than the corresponding alkanes.

192
Q

Why do alchohols have a higher boiling point than alkanes?

A

.Hydrogen bonding in alcohols gives higher boiling point

193
Q

Why does the gap bewteen boiling points start to narrow as the chain length incerases for alchohl and alkanes?

A

the significance of hydrogen bonding decreases, and London forces increase, therefore gap between boiling points starts to narrow

194
Q

Describe and explain solubility in alcohols

A

.Alcohols such as methanol and ethanol are soluble in water as hydrogen bonds form between the –OH group of the alcohol and the water molecules
.As the chain length increases, the influence of the –OH group decreases, and the solubility of the alcohol decreases
.Carbon chains are hydrophobic

195
Q

How can alcohols be classified?

A

primary, secondary and tertiary

196
Q

What does alcohol classification depend on?

A

depends on the number of hydrogen atoms and alkyl groups attached to the carbon atom that contains the alcohol function group

197
Q

Describe the structure of primary alcohols

A

.Primary has at least 2 hydrogens attached to the carbon with the alcohol group, plus either a carbon centre or another H

198
Q

Describe the structure of secondary alcohols

A

.Secondary has 1 hydrogens attached to the carbon with the alcohol group, plus 2 more carbon centres

199
Q

Describe the structure of tertiary alcohols

A

.Tertiary has 0 hydrogens attached to the carbon with the alcohol group, plus 3 more carbon centres

200
Q

What is an oxidising agent?

A

helps something to gain oxygen/lose electrons

201
Q

What can primary alcohols be oxidised into?

A

Aldehydes

202
Q

What is the formula for Sodium/potassium dichromate(VI)?

A

Na2Cr2O7

K2Cr2O7

203
Q

What colour is Cr2O7^2-?

A

Orange

204
Q

What colour is Cr^3+?

A

Green

205
Q

Cr2O7^2- + 14H^+ + 6e^- –>

A

2Cr^3+ + 7H2O

206
Q

When oxidising agents oxidise what happens to themselves?

A

They are reduced

207
Q

What does the oxidation of aldehydes lead to?

A

Carboxylic acid

208
Q

aldehyde + [o] –>

A

Carboxylic acid

209
Q

CH3CHO + [o] –>

A

CH3COOH

210
Q

Ethanol to ethanal is …

A

mild oxidation

211
Q

Ethanol to ethanoic acid is …

A

further oxidation

212
Q

What is required for further oxidation?

A

Reflux then distillation

213
Q

What is reflux?

A

continuous evaporation then condensation, where the reactants cannot escape the flask

214
Q

Alcohol + 2[o] –>

A

Carboxylic acid

215
Q

CH3CH2OH + 2[o] –>

A

CH3COOH + H2O

216
Q

What is [o]?

A

An oxidizing agent

217
Q

Structure of an aldehyde?

A

A carboxylic acid group but just H instead of OH

218
Q

Oxidation of secondary alcohol formula

A

Secondary alcohol + oxidising agent  ketone + water

219
Q

Can ketones be further oxidised?

A

No

220
Q

Why can’t tertiary alcohols be oxidised?

A

Due to lack of hydrogen on OH carbon

221
Q

Name 2 dehydrating agents, what does this mean?

A

Concentrated sulphuric acid (h2so4) or concentrated phosphoric acid (h3po4) are dehydrating agents i.e. they can remove water from molecules

222
Q

Cyclohexanol + H3PO4 –>

A

Cyclohexene

223
Q

What happens in dehyrdation reactions?

A

A hydrogen from the carbon with the OH group and a neigbouring arbon are removed

224
Q

Which haloalkanes have the strongest bond?

A

C-F, then C-Cl, then C-Br, then C-I

225
Q

Draw the mechanism of 2-bromobutane + :OH-

A

Check your notes

226
Q

What is a haloalkane?

A

C-X

X = F, Cl, Br, I

227
Q

Why are haloalkanes so reactive?

A

Halogens are very electronegative, so dipoles are formed, which makes them reactive

228
Q

What is a nucleophile?

A

donates a pair of electrons

229
Q

Example of nucleophile

A

hydroxide

230
Q

Equation for hydrolysis of haloalkane

A

Haloalkane + hydroxide  alcohol + halogen

231
Q

Factors affecting covalent bonds strength:

A
  • Shielding
  • Nuclear charge
  • Atomic radius
232
Q

For haloalkanes, why does hydrolysis increase in rate of reaction as you go down the group?

A

the strength of the bond between the halogen and the carbon becomes weaker as you go down the group.

233
Q

What is the practical for determining the rate of reaction for haloalkane?

A

Haloalkane + ethanol + silver nitrate, time for precipitate

234
Q

Draw HFC

A

Check notes

235
Q

What is the ozone layer doing now HFC’s have been introduced?

A

repairing, 3O2 –> 2O3

236
Q

Equations to show Nitrous oxide effect on ozone

A

NO- + O3 –> O2 + NO2-

NO2- + O3 –> NO- + 2O2

237
Q

Draw CFC

A

Check notes

238
Q

equations to show chlorine free radical effect on ozone

A

O3 + Cl- –> OCl- + O2

OCl- + O3 –> Cl- + 2O2

239
Q

Condensed version of chlorine free radical ozone equaions

A

2O3 –> 3O2

240
Q

What is the ozone layer

A

Ozone is a layer in the stratosphere which stops UV rays

241
Q

What is ozone

A

O3

242
Q

What are CFC’s

A

chlorofluorocarbons

243
Q

How is a Cl free radical formed from CFC’s

A

Weakest bond broken by UV rays from sun (C-Cl)

244
Q

What do we now use instead of CFC’s? Why?

A

We now instead use HFC’s (hydrofluorocarbons), which doesn’t make any free radicals, so the hole is now closing

245
Q

What do CFC’s do to ozone?

A

Turn it into` oxygen

246
Q

Halogenoalkane general formula

A

Cn¬H2n+1X

Where X is a halogen

247
Q

What are halogenoalkanes?

A

Halogenoalkanes are similar to alkanes but with one or more of the hydrogen atoms replaced by a halogen

248
Q

halogen prefixes

A

Fluorine Fluoro –
Chlorine Chloro –
Bromine Bromo –
Iodine Iodo –

249
Q

Number of groups prefixes

A 
One	-
Two	Di – 
Three	Tri –
Four	Tetra – 
Five	Penta –
250
Q

For halogenoalkanes, what is an r group?

A

A chain of carbon atoms can be represented by R when drawing the structure, this is referred to as an R group

251
Q

What is a primary haloalkane?

A
  • Primary (1’) halogenoalkanes

Have one R group attached to the carbon linked to the halogen

252
Q

What is a secondary haloalkane?

A
  • Secondary (2’) halogenoalkanes

Have two R groups attached to the carbon linked to the halogen

253
Q

What is a tertiary haloalkane?

A
  • Tertiary (3’) halogenoalkanes

Have three R groups attached to the carbon linked to the halogen

254
Q

Halogenoalkanes contain a polar carbon-halogen bond, the polarity arises from …

A

… the different electronegativity of the carbon and halogen atoms

255
Q

Halogen atoms are more electronegative than carbon atoms, the bonded electron pair is attracted more towards …

A

… halogen atom than towards the carbon atom

256
Q

Down the halogens, how does electronegativity change?

A

It decreases

257
Q

Describe how nucleophilic substitution can happen with haloalkanes

A
  • Nucleophiles (Nu-) attack the carbon of a carbon–halogen (C–X) bond, because the electron pair on the nucleophile is attracted towards the small positive charge on the carbon
  • The electrons in the C–X bond are repelled as the Nu- approaches the carbon atom
  • The Nu- bonds to the carbon and the C–X bond breaks. The two electrons move to the halogen, forming a halide ion
  • The halide is substituted, so this is a nucleophilic substitution reaction
258
Q

Give examples of nucleophiles

A

H2O, -OH, NH3

259
Q

When halogenoalkanes react with an aqueous solution of hot hydroxide ions, a nucleophilic substitution reaction occurs to produce …

A

… alcohol

260
Q

Hydrolysis is …

A

… a reaction with water or aqueous hydroxide ions that breaks a chemical compound into two compounds

261
Q

How can the rates of hydrolysis reactions of haloalkanes be measured?

A

.Alkaline hydrolysis with NaOH(aq)/H2O, reflux:
R-X + OH-  R-OH + X-
.Acidification with dilute nitric acid, this removes excess NaOH which would otherwise form a precipitate with the silver nitrate in the next stage, preventing detection of any silver halides
.Addition of AdNO3(aq) ¬shows the presence of aqueous halide ions
Ag+(aq) + X-(aq)  AgX(S)

262
Q

For haloalkane hydrolysis, the intensity of the precipitate indicates …

A

… the extent and rate of the hydrolysis

263
Q

Method of rates of hydrolysis investigatio n

A
  1. Set up water bath to a temperature of 50’C at the start of the lesson
  2. Set up five test tubes and allow them to reach 50 ‘C
  3. Place a separate test tube containing silver nitrate into the water bath and allow this to reach the same temperature
  4. One tube at a time, add 1cm3 of the silver nitrate solution, mix the contents and start the timer
  5. Note the time it takes for a precipitate to form
  6. Repeat this with the other tubes and note the results
264
Q

Why is ethanol used for hydrolysis practical of halogenoalkanes?

A
  1. Halogenoalkanes are insoluble in water, but soluble in ethanol
265
Q

What is the ozone layer and what does it do?

A

.A high concentration of O3 molecules about 15-30Km above the Earth’s surface
.Ozone absorbs a high proportion of the Sun’s ultraviolet radiation

266
Q

.If there was a lower concentration of ozone in the stratosphere, then …

A

… ultraviolet radiation would manage to get to Earth, and cause harm to us through burns and skin cancer

267
Q

.The Ozone layer goes through a cycle of reaction that are altered by …

A

… the addition of halogenoalkanes in the atmosphere

268
Q

Link between ozone depletion and global warming?

A

OZONE DEPLETION IS NOTHING TO DO WITH GLOBAL WARMING

269
Q

What are chlorofluorocarbons? Examples

A

.Chlorofluorocarbons are a family of organic compounds that contain chlorine atoms and fluorine atoms, examples include dichlorodifluoromethane and 1, 1, 1-trichloro-2, 2, 2-trifluoroethane

270
Q

.In the 1930’s, CFC’s were developed for use as …

A

… refrigerants, to cool the air inside refrigerators

.They were also found to be useful in other products like aerosol sprays and form fire extinguishers

271
Q

.They are inert, and used to be widely used as …

A

… they do not react with other substances

272
Q

.At ground level, CFC’s are very stable, but once they …

A

… reach the atmosphere they absorb UV radiation from the Sun which breaks their covalent bonds to form highly reactive free radicals

273
Q

What do free radicals from CFC’s do?

A

These react very quickly with ozone molecules in a free radical chain reaction

274
Q

just one chlorine radical can destroy around _______ ozone molecules

A

100,000

275
Q

CFC reaction with Ozone in steps

A

Initiation –
.The UV breaks the weaker C-Cl bond within the CFC molecule
.CF2Cl2 -> CF2Cl + Cl ●
Propagation –
.The chlorine radical Cl’ is very reactive and reacts with ozone molecules
.Cl ● + O3 -> ClO ● + O2 step 1
.ClO ● + O3 -> Cl ● + 2O2 step 2
.Propagation step 2 regenerates a Cl’ free radical, so the 2 steps repeat in a cycle over and over again

276
Q

CFC reaction with ozone overall equation

A

O3 + O –> 2O2

277
Q

What led to the Motreal Protocol, what was the Montral Protocol and what was its effect?

A

.The effect of CFC’s on the Ozone layer was established in the 1970’s
.In 1987, an international agreement called the Montreal Protocol was put in place – it froze the production of CFC’s and agreed to phase out their use from 1990
.Since CFC’s are so stable, it will be many years till they disappear from the atmosphere
.Some Ozone depletion has therefore continued since the phasing out of CFC’s

278
Q

What is distillation?

A

a separating technique that is used to collect a product from an organic synthesis reaction

279
Q

What is reflux?

A

a technique used in organic synthesis to ensure that a reaction mixture does not boil away

280
Q

To heat under reflux you need:

A

.Pear-shaped flask
.Heating mantle
.Condenser

281
Q

Method for using a seperating funnel:

A
  1. Mount an iron ring on a clamp stand and put the separating funnel in it.
  2. Remove the stopper and make sure that the tap at the bottom is closed.
  3. Carefully pour the mixture into the funnel so that the funnel is no more than half full. Wash out the reaction vessel with water and add this to the mixture in the funnel – there should still be some air in the funnel. Put the stopper back.
  4. Take the funnel out of the ring and invert it. Open the tap to equalise the pressure. Turn the tap back to closed. Gently shake the mixture in the funnel and equalise the pressure as required. Repeat until you no longer hear a ‘whistle’.
  5. Replace the funnel in the iron ring and give the mixture time to separate into layers.
  6. Remove the stopper, put a beaker under the spout and open the tap. Collect the lower (water) layer in a beaker. Turn the tap off. As the organic product is in the upper layer, this aqueous layer can be discarded.
  7. Using a clean, dry beaker open the tap and collect the desired organic product.
  8. Shake the liquid with a small amount of drying agent and pour the final dry product into a clean, dry container.
282
Q

What are drying agents, with examples, and how do you use them?

A

Inorganic salts such as magnesium sulphate (MgSO4) and calcium chloride (CaCl2) absorb water slowly to become hydrated. The anhydrous salts can be used to dry other chemicals:
.Add a few spatulas of the drying agent to the organic product
.If the drying agent clumps together, add some more
.When the drying agent remains free-moving the organic product is dry
.Use gravity filtration and collect the filtrate, which is the dry organic product

283
Q

What is redistillation?

A

the purification of a liquid by performing multiple distillations

284
Q

Example of when redistillation is used?

A

For instance, when ethanol is made by fermentation, distillation is used to remove the ethanol from the mixture of water, yeast and any remaining sugar, then the distillate is usually distilled again to purify the ethanol further

285
Q

List and draw the needed functional groups for year 12

A

Check notes

286
Q

For the functional group of unsaturated hydrocarbon, list the reagents and observation

A

.Add a few drops of bromine water to the sample and shake

.Bromine water decolourises

287
Q

What happens when you mix a carbonyl and acidified potassium dichromate (VI)

A

Ketones - no change

Aldehydes - orange turns green

288
Q

What happens when you mix carbonyl and fehling solution?

A

Ketones - no change

Aldehydes - dark red precipitate

289
Q

What happens when you mix carbonyl and tollens’ reagent?

A

Ketons - no silver mirror

Aldehydes - silver mirror

290
Q

What happens when you mix carboxylic acid with a reactive metal?

A

effervescence (hydrogen)

291
Q

What happens when you mix carboxylic acid with a metal carbonate?

A

effervescence (carbon dioxide)

292
Q

What happens when you mix alcohol (warm) with an equal volume of carboxylic acid and a few drops of H2SO4?

A

Sweet smell of an ester after a short time

293
Q

Give an example of a compound with multiple functional groups

A

Paracetamol, aspirin, niacin

294
Q

What happens to the reactivity of functional groups when there are multiple in a compound?

A

The chemical reactivity of each functional group is usually the same as it would be on its own

295
Q

What is aspirin?

A

Aspirin is an analgesic (painkiller) and was original obtained from willow bark. It has a number of functional groups including a carboxylic acid and an aromatic ring

296
Q

What is Niacin?

A

Vitamins help our bodies to work more efficiently. Many vitamins are complex organic molecules with several functional groups. Vitamin B3, also known as niacin, has the IUPAC name pyridine-3-carboxylic acid. It is needed for healthy hair, eyes, skin and liver. This organic molecule contains nitrogen in a stable structure known as a pyridine ring and a carboxylic acid functional group.

297
Q

Draw the synthetic routes

A

check notes

298
Q

Uses of Mass spectroscopy

A
  • Identify molecular mass of unknown compounds
  • Determine the abundance of each isotope in an element
  • Gain information about the structure and chemical properties of molecules
299
Q

Modern uses of mass spectroscopy

A
  • Monitor breath of patients during surgery
  • Detecting banned substances in athletes
  • Analysing molecules in space
  • Detecting toxic chemicals in marine life
300
Q

How is mass spectroscopy used in space? example

A

.Mass spectrometers have been included on-board several space probes
.In 2005, the Huygens probe landed on the surface of Titan, the largest moon of Saturn

301
Q

What did the Huygens probe find out about the atmosphere of Titan?

A

.During the descent towards the surface of Titan, the mass spectrometer analysed the atmospheric composition at various heights, it was found that the atmosphere consists of mainly nitrogen and methane but the presence of argon-40 was also detected

302
Q

What does a mass spectroscopy do?

A

.Determines the mass of a molecule or isotope by measuring mass to charge ratio of ions

303
Q

How, basically, does a mass spectroscopy work?

A

.Sample introduced via a sample inlet
.Ionisation of sample by electron impact, chemical ionisation, electrospray or laser
.Ions accelerated into mass analyser
.Ions separated due to mass-to-charge ratio by deflection from magnetic field or time of flight
.Ions detected and spectrum generated by computer

304
Q

Steps of mass spectroscopy

A

Vaporisation, ionisation, acceleration, deflection, detection

305
Q

In depth how does mass spectroscopy work

A

.Vaporization – the sample material is introduced into the spectrometer as a gas, solid samples first need to be heated and vaporized
.Ionisation – As the sample vapour passes across the electron beam, high-energy electrons in the beam knock out electrons in the sample atoms, ionizing them into positive ions
.Acceleration – an electric field is created using a series of negatively charged plates, the positive ions are attracted towards these plates and accelerated towards an electromagnet
.Deflection – the electromagnet creates an electromagnetic field (EMF) that deflects the ions, the amount by which they are deflected depends on their mass to charge ration (m/z) (high m/z deflects a small amount, low m/z deflects a large amount, specific m/z deflected to the collection plate), ions with a specific m/s for a given strength of the EMF are deflected through a slit in a negatively-charged collector plate onto a detector screen
.By varying the strength of the EMF, ions with different m/z values can be deflected through a narrow slit and on to the collector plate
.Detection – Once ions strike the collector they induce a current, which is amplified and converted into a mass spectrum, the more ions of a particular m/z, the greater the current and the larger the peak

306
Q

What happens when molecules become ionised in mass spectroscopy? Example equation

A

Molecules become ionised and lose an e-, giving a molecule ion M+
C2H5OH + e-  C2H5OH+ + e-

307
Q

In mass spectroscopy, is the mass loss of e- noticeable?

A

.The mass loss of e- is negligible

308
Q

In mass spectroscopy, molecular ion mass =

A

.Molecular ion mass = molecular mass of compound

309
Q

In mass spectroscopy, what is detected and analysed?

A

.Molecular ion detected and analysed

310
Q

How is fragmentation caused in mass spectroscopy? Example

A

.Excess energy from ionisation can be transferred to molecular ion making it vibrate
.This can cause bonds to weaken and can split molecular ions into fragments (fragmentation)
C2H5OH+  CH3 + CH2OH+

311
Q

Are molecular ion fragments detected in mass spectroscopy?

A

Yes

312
Q

How can unknown compounds be identified with mass spectroscopy?

A

.Although the molecular ion peak for 2 isomers will be the same m/z value, fragmentation patterns will be different
.Each organic compound has a unique mass spectroscopy, which can be used as a ‘fingerprint’ for identification

313
Q

How can you get molecular mass from mass spectroscopy?

A

The peak with the highest m/z is formed by the molecular ion, and the value of m/z is equal to the relative molecular mass of the compound
.The peak at the highest m/z on the mass spectrum is formed by the heaviest ion that passes through the spectrometer
.Unless all molecules of the original substance break up, this corresponds to the molecular ion of the sample substance

314
Q

.Although MS can be analysed by viewing it is now often linked to a …

A

… database and a match found which gives identification of an unknown compound

315
Q

What is the M+1 peak?

A

.You will also see a very small peak one unit after the M+ peak, this is referred to as the M+1 peak

316
Q

Why is the M+1 peak there?

A

.The M+1 peak exists as 1.1% of carbon is present as the carbon-13 isotope, this will mean a small number of molecules have a carbon-13 atom, and hence a mass one unit greater than the Mr (M peak)

317
Q

Number of carbon atoms =

A

((height of M+1 peak)/(height of M peak)) x 100

318
Q

What can high resolution mass spectrometery not do?

A

High resolution mass spectrometry cannot differentiate between structural isomers using the M+ peak alone

319
Q

Covalent bonds can absorb what?

A

Infrared energy

320
Q

.Different bonds absorb different __________ of infrared energy

A

wavelengths

321
Q

Bonds can also vibrate in different ways – these are called what?

A

Molecular vibrations

322
Q

Methanal can undergo symmetrical stretching of the carbon-hydrogen bonds, what does this mean?

A

this means that both carbon-hydrogen bonds stretch in time with each other

323
Q

Methanal can undergo asymmetrical stretching of the carbon-hydrogen bonds, what does this mean?

A

this means that the carbon-hydrogen bonds stretch out of time with each other

324
Q

Methanals carbon-oxygen bond can also stretch as a result of what?

A

absorbing infrared energy

325
Q

.Carbon hydrogen bonds can also absorb infrared energy causing them to …

A

… bend

326
Q

.Different types of stretches and bends are caused by different _________ of infrared energy

A

wavelengths

327
Q

.Energy from infrared radiation is only transferred to a bond if …

A

… the bond has a dipole that changes as it vibrates

328
Q

Does the symmetical stretch in carbon dioxide occur? Why?

A

.The symmetrical stretch in carbon dioxide does not result in an overall change in dipole of the molecules so no IR energy is transferred to the bonds

329
Q

Does the asymmetical stretch in carbon dioxide occur? Why?

A

.The asymmetrical stretch in carbon dioxide does result in an overall change in dipole of the molecule, so IR energy is transferred to the bonds

330
Q

Does the bending in carbon dioxide occur? Why?

A

.The bending vibration in carbon dioxide does result in an overall change in dipole of the molecule, so IR energy is transferred to the bonds

331
Q

.One asymmetrical stretch and one bend will both result in a change in the overall dipole, and so are said to be what?

A

IR Active

332
Q

.The IR spectrum of carbon dioxide shows what? why?

A

two absorption due to these vibrations (asymmetrical and bending)

333
Q

.On absorbing infrared radiation bonds will vibrate, either _____ or _____

A

bending or stretching

334
Q

.Every bond vibrates with a unique frequency, this is picked up by the …

A

… spectrometer

335
Q

Vibration depends on what?

A
  • Bond strength
  • Bond length
  • Mass of the bonded atoms
336
Q

What does an infrared spectrometer do?

A

.An infrared spectrometer records the frequencies of infrared energy absorbed by a sample

337
Q

How does an infrared spectrometer work?

A

.The sample of solid or liquid is prepared by being pressed between two salt plates, which are transparent to infrared radiation
.The sample is placed in the infrared spectrometer and the cover is closed
.Infrared radiation is fired at the sample, some frequencies are absorbed, while the remaining frequencies pass through and are registered by the detector on the far side of the sample
.The radiation that doesn’t pass through has been absorbed by bonds in the material, causing them to stretch and/or bend, the pattern of frequencies absorbed is unique to the substance being tested
.The results of the spectroscopy are plotted on a screen as a graph of percentage transmission of radiation against wavenumber

338
Q

Draw a diagram of an infrared spectrometer

A

check notes

339
Q

For infrared spectrometery, what is a peak?

A

A peak (downwards is still a peak) is characteristic of a vibration of a particular group

340
Q

How do breathalyzers work at the station?

A

.At the police station, the motorist blows into a more accurate breathalyzer, containing an IR spectrometer
.The breathalyzer calculates the percentage of alcohol in the breath by looking at the size of the absorption due to the C–H bond stretch in the alcohol

341
Q

How can infrared spectrometery b used in forensic science?

A

to analyse paint fragments from vehicles in hit-and-run offences

342
Q

What are some uses of infrared spectrometery?

A
  • Monitoring the degree of unsaturation in polymers
  • Quality control in perfume manufacture
  • Drug analysis
343
Q

Bond: C-O
Location:
Wavenumber (cm-1):

A

Location: Alcohols, esters, carboxylic acids

Wavenumber (cm-1): 1000-1300

344
Q

Bond: C=O
Location:
Wavenumber (cm-1):

A

Location: Aldehydes, ketones, carboxylic acids, esters, amides
Wavenumber (cm-1): 1640-1750

345
Q

Bond: C-H
Location:
Wavenumber (cm-1):

A

Location: Organic compounds with a C-H bond

Wavenumber (cm-1): 2850-3100

346
Q

Bond: O-H
Location:
Wavenumber (cm-1):

A

Location: Carboxylic acids

Wavenumber (cm-1): 2500-3300 (very broad)

347
Q

Bond: N-H
Location:
Wavenumber (cm-1):

A

Location: Amines, amides

Wavenumber (cm-1): 3200-3500

348
Q

Bond: O-H
Location:
Wavenumber (cm-1):

A

Location: Alcohols, phenols

Wavenumber (cm-1): 3200-3550 (broad)

349
Q

What are important functional groups to know for IR spectrometry AS?

A
  • O-H (hydroxyl) group for alcohols
  • C=O (carbonyl) group for aldehydes and ketones
  • COOH (carboxyl) group in carboxylic acids
350
Q

What is an infrared spectrum?

A

.An infrared spectrum is a plot of transmission of infrared radiation against wavenumber

351
Q

What is wavenumber?

A

1/wavelength

352
Q

What are dips in IR spectrums caused by?

A

.Any wavelength that is absorbed by the sample will transmit less than the others, forming a dip or ‘peak’ in he graph

353
Q

What do peaks at different points on IR spectrums represent?

A

.Peaks at different wavenumbers identify different functional groups

354
Q

What is the fingerprint region on an IR spectrum and where is it?

A

.The region below 1500cm-1, usually called the fingerprint region, has many peaks that are difficult to assign
.The pattern of these peaks is unique to a particular compound

355
Q

What is the units of wavenumber?

A

Cm-1

356
Q

How can a substance be identified from its fingerprint region?

A

.A substance may be identified by comparing the IR spectrum to a database of reference spectra
.An exact match in the fingerprint region identifies a compound

OCR A Level Chemistry (17 decks)

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