1
Q
What type of hydrocarbons are alkenes classified as?
A
Unsaturated hydrocarbons
They contain at least one carbon–carbon double bond.
2
Q
What type of bond is present between carbon atoms in alkenes?
A
Double covalent bond
The C=C bond consists of one σ bond and one π bond.
3
Q
Fill in the blank:
The carbon–carbon double bond in alkenes is a region of high _______ density.
A
electron
This makes alkenes more reactive than alkanes.
4
Q
True or False:
Alkenes are more reactive than alkanes due to the presence of a double bond.
A
True
The electron-rich double bond attracts electrophiles.
5
Q
What are the two types of bonds present in a carbon–carbon double bond?
A
Sigma and pi
The σ bond forms by head-on overlap and the π bond by sideways overlap.
6
Q
True or False:
The π bond in alkenes is stronger than the σ bond.
A
False
The π bond is weaker and more easily broken in reactions.
7
Q
Fill in the blank:
The double bond in alkenes restricts _______ about the carbon–carbon bond.
A
rotation
This restriction leads to E–Z stereoisomerism.
8
Q
Why do alkenes undergo many addition reactions?
A
High electron density
The π bond attracts electrophiles.
9
Q
True or False:
The electron density in an alkene is concentrated above and below the plane of the molecule.
A
True
This is due to the π bond formed by sideways overlap of p orbitals.
10
Q
Fill in the blank:
The π bond is formed by sideways overlap of _______ orbitals.
A
p
These orbitals form electron density above and below the bond axis.
11
Q
What type of reactions are typical for alkenes due to their double bond?
A
Addition reactions
The π bond breaks allowing new atoms to add across the double bond.
12
Q
Why is the double bond in alkenes considered a reactive site?
A
Electron-rich region
The high electron density attracts electron-deficient species.
13
Q
What type of reaction commonly occurs when alkenes react with small molecules such as HBr or Br2?
A
Electrophilic addition
The π bond breaks and atoms add across the C=C bond.
14
Q
What type of species attacks the electron-rich double bond in alkenes?
A
Electrophile
Electrophiles are electron-pair acceptors attracted to high electron density.
15
Q
Fill in the blank:
In electrophilic addition, the alkene double bond acts as a source of _______.
A
electrons
The π bond donates electrons to the electrophile.
16
Q
True or False:
Bromine water can be used to test for unsaturation in organic molecules.
A
True
Alkenes decolourise orange bromine water.
17
Q
What observation indicates the presence of a carbon–carbon double bond when bromine water is added?
A
Decolourisation
The orange colour disappears as bromine reacts with the alkene.
18
Q
True or False:
Electrophilic addition reactions proceed through a carbocation intermediate.
A
True
The intermediate forms after the electrophile attacks the double bond.
19
Q
Fill in the blank:
The positively charged intermediate formed during electrophilic addition is called a _______.
A
carbocation
Its stability influences which product forms.
20
Q
Which carbocation is most stable: primary, secondary, or tertiary?
A
Tertiary
Tertiary carbocations are stabilised by surrounding alkyl groups. This is because alkyl groups have a positive inductive effect.
21
Q
True or False:
The most stable carbocation usually leads to the major product of the reaction.
A
True
Reaction pathways favour the most stable intermediate.
22
Q
Fill in the blank:
When an unsymmetrical alkene reacts with HBr, the hydrogen attaches to the carbon with the _______ hydrogens.
A
most
This forms the more stable carbocation intermediate.
23
Q
What term describes the main product formed in a reaction when multiple products are possible?
A
Major product
It forms through the most stable reaction pathway.
24
Q
Why can minor products form during electrophilic addition reactions?
A
Alternative carbocation formation
Less stable intermediates can still form in smaller amounts.
25
What type of **polymer** is formed when many **alkene molecules join together**?
Addition polymer
## Footnote
The polymer forms when the C=C double bonds open and link monomers together.
26
What is the **small molecule** that joins repeatedly to form a **polymer** called?
Monomer
## Footnote
Monomers are the repeating building blocks of polymers.
27
# Fill in the blank:
In **polymer chemistry**, the repeating section of a polymer chain is called the _\_\_\_\_\_\_ unit.
repeating
## Footnote
It shows the smallest part of the polymer structure that repeats.
28
# True or False:
**Addition polymers** are formed **without the loss of small molecules**.
True
## Footnote
No by-products are produced during addition polymerisation.
29
What happens to the **carbon–carbon double bond** during addition polymerisation?
It opens
## Footnote
The π bond breaks allowing monomers to join into a long chain.
30
# True or False:
**Addition polymers** are generally **chemically unreactive**.
True
## Footnote
They contain strong C–C and C–H bonds that require a lot of energy to break and no reactive functional groups.
31
# Fill in the blank:
**Poly(chloroethene)** is commonly known as _\_\_\_\_\_\_.
PVC
## Footnote
It is widely used in pipes, cables and construction materials.
32
What **substance** can be added to **PVC** to make it more flexible?
Plasticiser
## Footnote
Plasticisers reduce intermolecular forces between polymer chains.
33
# True or False:
**Polyalkenes** are held together mainly by **strong ionic bonds** between molecules.
False
## Footnote
Intermolecular forces between chains are mainly van der Waals forces.
34
# Fill in the blank:
Intermolecular attractions between **polyalkene chains** are mainly _\_\_\_\_\_\_ forces.
Van der Waals
## Footnote
These weak forces act between long hydrocarbon chains.
35
Why are **addition polymers** generally **chemically inert**?
Strong covalent bonds
## Footnote
The polymer backbone contains strong C–C and C–H bonds.
36
What must be done to an **alkene monomer** to identify the **repeating unit of the polymer**?
Break the double bond
## Footnote
The C=C bond opens and forms two single bonds in the polymer chain.
37
What **industrial process** produces **alcohols from alkenes**?
Hydration
## Footnote
Steam adds across the C=C bond in the presence of an acid catalyst.
38
What type of **reaction** converts an **alkene into an alcohol using steam**?
Electrophilic addition
## Footnote
The alkene double bond reacts with steam to form an alcohol.
39
# Fill in the blank:
In **industrial hydration**, alkenes react with _\_\_\_\_\_\_ to produce alcohols.
steam
## Footnote
This reaction uses an acid catalyst such as phosphoric acid.
40
# True or False:
**Ethanol** can be produced biologically from **glucose by fermentation**.
True
## Footnote
Yeast enzymes convert glucose into ethanol and carbon dioxide.
41
What **microorganism** is commonly used to **ferment glucose to ethanol**?
Yeast
## Footnote
Yeast contains enzymes that catalyse the fermentation reaction.
42
# Fill in the blank:
The **fermentation of glucose** produces ethanol and _\_\_\_\_\_\_.
carbon dioxide
## Footnote
C6H12O6 → 2C2H5OH + 2CO2.
43
# True or False:
**Fermentation** occurs efficiently at **temperatures around 30–40 °C**.
True
## Footnote
Higher temperatures can kill the yeast enzymes.
44
What **process** is used to separate **ethanol from the fermentation mixture**?
Fractional distillation
## Footnote
Ethanol is separated based on its boiling point.
45
# Fill in the blank:
A **fuel produced from biological sources** such as plants is called a _\_\_\_\_\_\_ fuel.
biofuel
## Footnote
Biofuels are derived from renewable biological materials.
46
Why is **ethanol** sometimes described as a **carbon-neutral fuel**?
Carbon cycle balance
## Footnote
CO2 released during combustion equals CO2 absorbed during plant growth.
47
# True or False:
**Ethanol produced by fermentation** is perfectly **carbon neutral in practice**.
False
## Footnote
Energy used in farming, processing and transport releases additional CO2.
48
Why must **fermentation** occur in the **absence of oxygen**?
Prevent oxidation
## Footnote
Oxygen would allow yeast to respire aerobically instead of producing ethanol.
49
How are **alcohols** classified according to the **carbon atom bonded to the –OH group**?
* Primary
* Secondary
* Tertiary
## Footnote
Classification depends on how many carbon atoms are attached to the carbon bearing the –OH group.
50
What type of **alcohol** has the **–OH group** attached to a carbon bonded to only one other carbon?
Primary alcohol
## Footnote
Example: ethanol.
51
# Fill in the blank:
A **secondary alcohol** has the –OH group attached to a carbon bonded to _\_\_\_\_\_\_ other carbons.
two
## Footnote
The central carbon is connected to two alkyl groups.
52
# True or False:
**Tertiary alcohols** are easily **oxidised** under normal laboratory conditions.
False
## Footnote
They resist oxidation because the –OH carbon lacks a hydrogen atom.
53
What **oxidising agent** is commonly used to oxidise alcohols in the laboratory?
Acidified potassium dichromate
## Footnote
K2Cr2O7 in acidic conditions is a common oxidising agent.
54
# True or False:
**Primary alcohols** can be oxidised first to **aldehydes and then to carboxylic acids**.
True
## Footnote
Further oxidation occurs if strong oxidising conditions are used.
55
# Fill in the blank:
Oxidation of a **secondary alcohol** produces a _\_\_\_\_\_\_.
ketone
## Footnote
The carbon–oxygen double bond forms at the alcohol carbon.
56
What determines whether a **primary alcohol** forms an **aldehyde or a carboxylic acid** during oxidation?
Reaction conditions
## Footnote
Distillation forms aldehydes; reflux allows further oxidation to acids.
57
# True or False:
**Distillation** is used during oxidation to collect **aldehydes before they oxidise further**.
True
## Footnote
Aldehydes have lower boiling points and can be removed from the reaction mixture.
58
# Fill in the blank:
The reagent that produces a **silver mirror with aldehydes** is _\_\_\_\_\_\_ reagent.
Tollens
## Footnote
Aldehydes reduce [Ag(NH3)2]+ to metallic silver.
59
What **observation** occurs when **Fehling’s solution reacts with an aldehyde**?
Brick red precipitate
## Footnote
The aldehyde reduces Cu2+ to Cu2O.
60
Why do **ketones** not react with **Tollens’ reagent**?
Not easily oxidised
## Footnote
Ketones lack the hydrogen needed for oxidation under these conditions.
61
What type of **reaction** forms an **alkene from an alcohol** by removing water?
Elimination
## Footnote
The alcohol loses H2O to form a C=C double bond.
62
What **molecule** is removed from an **alcohol during elimination** to form an alkene?
Water
## Footnote
The reaction is often called dehydration of an alcohol.
63
# Fill in the blank:
**Acid-catalysed elimination** of alcohols produces _\_\_\_\_\_\_.
alkenes
## Footnote
A double bond forms between adjacent carbon atoms.
64
# True or False:
**Elimination of alcohols** requires an **acid catalyst**.
True
## Footnote
Concentrated acids such as H2SO4 or H3PO4 are typically used.
65
What **role** does the **acid** play in the elimination of water from alcohols?
Catalyst
## Footnote
It helps protonate the –OH group to make water a better leaving group.
66
# True or False:
The **–OH group** in alcohols is converted into **water before leaving the molecule**.
True
## Footnote
Protonation forms H2O, which can leave more easily than OH-.
67
# Fill in the blank:
In the **elimination mechanism**, the alcohol is first _\_\_\_\_\_\_ to form a better leaving group.
protonated
## Footnote
The –OH group gains a proton to become H2O.
68
What **structural change** occurs in the molecule during **elimination of an alcohol**?
Double bond formation
## Footnote
A C=C bond forms after removal of H2O.
69
# True or False:
**Alkenes produced from alcohols** can be used to make **addition polymers**.
True
## Footnote
These alkenes can act as monomers in polymerisation reactions.
70
# Fill in the blank:
The **elimination of water from alcohols** is also called _\_\_\_\_\_\_.
dehydration
## Footnote
This term refers to removal of H2O from the molecule.
71
What **laboratory technique** is used to purify **cyclohexene produced from cyclohexanol**?
Distillation
## Footnote
The alkene is separated based on its boiling point.
72
Why is producing **alkenes from alcohols** environmentally beneficial compared with crude oil sources?
Renewable feedstocks
## Footnote
Alcohols can be derived from biomass rather than fossil fuels.
73
What equation shows **CO₂ absorption during photosynthesis** (production of ethanol source)?
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
74
What equation shows **fermentation of glucose to produce ethanol**?
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
75
What equation shows **combustion of ethanol**?
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
76
What is the **general oxidation equation** for a **primary alcohol to an aldehyde**?
RCH₂OH + [O] → RCHO + H₂O
77
What is the **general oxidation equation** for an **aldehyde to a carboxylic acid**?
RCHO + [O] → RCOOH
78
What is the **oxidation equation for a secondary alcohol**?
R₁CHOHR₂ + [O] → R₁COR₂ + H₂O
79
What is the **overall oxidation equation** for a **primary alcohol to a carboxylic acid**?
RCH₂OH + 2[O] → RCOOH + H₂O
80
What **functional group** is present in **carboxylic acids**?
Carboxyl
## Footnote
The –COOH group contains both a carbonyl and hydroxyl group.
81
What type of **compounds** are formed when a **carboxylic acid reacts with an alcohol**?
Esters
## Footnote
The reaction is known as esterification.
82
# Fill in the blanks:
**Carboxylic acids** react with **carbonates** to release _\_\_\_\_\_\_ _\_\_\_\_\_\_ gas.
carbon dioxide
## Footnote
This reaction forms CO2, water and a salt.
83
# True or False:
**Carboxylic acids** are **strong acids** in aqueous solution.
False
## Footnote
They are weak acids and only partially dissociate.
84
What **catalyst** is commonly used in **esterification reactions**?
Concentrated sulfuric acid
## Footnote
It acts as an acid catalyst and dehydrating agent.
85
# True or False:
**Esters** often have **distinctive fruity smells**.
True
## Footnote
This is why they are used in perfumes and food flavourings.
86
# Fill in the blank:
**Esters** can be hydrolysed in **alkaline conditions** to produce an alcohol and a _\_\_\_\_\_\_ of a carboxylic acid.
salt
## Footnote
The salt forms because the acid reacts with the alkali.
87
What type of **molecules** are **vegetable oils and animal fats** chemically classified as?
Esters
## Footnote
They are esters formed from glycerol and fatty acids.
88
# True or False:
**Soap** is produced by **alkaline hydrolysis of fats and oils**.
True
## Footnote
This process is called saponification.
89
# Fill in the blank:
**Hydrolysis of fats** in alkaline solution produces glycerol and _\_\_\_\_\_\_.
soap
## Footnote
Soap consists of salts of long-chain carboxylic acids.
90
What **substance** reacts with **vegetable oils** to produce biodiesel?
Methanol
## Footnote
A catalyst is used to form methyl esters.
91
What type of **compounds** make up **biodiesel**?
Methyl esters
## Footnote
These esters are derived from long-chain fatty acids.
92
What **functional group** is present in **acyl chlorides**?
Acyl chloride
## Footnote
The functional group has the structure –COCl.
93
What **functional group** links two **acyl groups together** in acid anhydrides?
Anhydride linkage
## Footnote
The structure contains –CO–O–CO–.
94
# Fill in the blank:
A **primary amide** contains the functional group _\_\_\_\_\_\_.
–CONH2
## Footnote
Amides contain a carbonyl group attached to nitrogen.
95
# True or False:
**Acyl chlorides** are highly reactive towards **nucleophiles**.
True
## Footnote
The C–Cl bond is easily attacked due to the electron-withdrawing chlorine.
96
What type of **reaction** occurs when **acyl chlorides react with nucleophiles**?
Nucleophilic addition–elimination
## Footnote
The nucleophile adds to the carbonyl carbon then a leaving group is eliminated.
97
# True or False:
**Acyl chlorides** react with **water to form carboxylic acids and HCl**.
True
## Footnote
The reaction also produces hydrogen chloride gas.
98
# Fill in the blank:
Reaction of an **acyl chloride with an alcohol** produces an _\_\_\_\_\_\_.
ester and HCl
## Footnote
The alcohol replaces the chlorine atom.
99
What **product** forms when an **acyl chloride reacts with ammonia**?
Amide
## Footnote
Ammonia acts as a nucleophile and replaces the chloride. This reaction also produces HCl gas.
100
# True or False:
**Primary amines** reacting with **acyl chlorides** produce **N-substituted amides**.
True
## Footnote
The –NH2 group acts as the nucleophile.
101
# Fill in the blank:
In **nucleophilic addition–elimination reactions**, the nucleophile first attacks the _\_\_\_\_\_\_ carbon.
carbonyl
## Footnote
This forms a tetrahedral intermediate.
102
Why is **ethanoic anhydride** often preferred to **ethanoyl chloride** in aspirin manufacture?
Safer and less corrosive as it doesn't produce toxic HCl gas
## Footnote
It produces fewer hazardous by-products.
103
What type of **molecule** acts as the **nucleophile in acylation reactions**?
Electron pair donor
## Footnote
Examples include water, alcohols and amines.
104
Give 4 common uses of esters
* solvents
* plasticisers
* perfumes
* food flavourings
## Footnote
They are good polar solvents due to their polar nature. They are good plasticisers as they can slide in between polymer chains. They are good perfumes and food flavourings due to their sweet smell.
105
What type of **isomerism** occurs when molecules differ in their effect on **plane-polarised light**?
Optical isomerism
## Footnote
This occurs due to chirality in molecules.
106
What type of **carbon atom** causes **optical isomerism** in organic molecules?
Chiral carbon
## Footnote
A carbon bonded to four different groups.
107
# Fill in the blank:
A **carbon atom** attached to four different groups is called an _\_\_\_\_\_\_ carbon.
asymmetric
## Footnote
This type of carbon atom is also described as **chiral**.
108
# True or False:
**Optical isomerism** is a form of **stereoisomerism**.
True
## Footnote
The molecules have the same structural formula but differ in spatial arrangement.
109
What name is given to **optical isomers** that are **non-superimposable mirror images**?
Enantiomers
## Footnote
They rotate plane-polarised light in opposite directions.
110
# True or False:
**Enantiomers** have identical physical properties except for their interaction with **plane-polarised light**.
True
## Footnote
They may also behave differently in biological systems.
111
# Fill in the blank:
**Optical isomers** differ in the direction they rotate _\_\_\_\_\_\_ polarised light.
plane
## Footnote
One rotates light clockwise and the other anticlockwise.
112
What is a mixture containing **equal amounts of two enantiomers** called?
Racemic mixture
## Footnote
Also known as a racemate.
113
# True or False:
A **racemic mixture** rotates **plane-polarised light**.
False
## Footnote
Equal and opposite rotations cancel each other out.
114
# Fill in the blank:
A **racemic mixture** is optically _\_\_\_\_\_\_.
inactive
## Footnote
The effects of the two enantiomers cancel out.
115
Why are **enantiomers** described as **non-superimposable mirror images**?
Different spatial arrangement
## Footnote
The molecules cannot be aligned exactly even when mirrored - they are non superimposable mirror images of one another
116
What **property of a molecule** leads to **optical isomerism**?
Chirality
## Footnote
A chiral molecule lacks a plane of symmetry and has a chiral centre.
117
What **functional group** is present in both **aldehydes and ketones**?
Carbonyl
## Footnote
The carbonyl group consists of a C=O double bond.
118
What type of **species** commonly attacks the **carbonyl carbon** in aldehydes and ketones?
Nucleophile
## Footnote
The carbonyl carbon is partially positive and susceptible to nucleophilic attack.
119
# Fill in the blank:
The **carbon atom** in the carbonyl group has a partial _\_\_\_\_\_\_ charge.
positive
## Footnote
The electronegative oxygen pulls electron density away from carbon.
120
# True or False:
**Aldehydes** are more easily **oxidised** than ketones.
True
## Footnote
Aldehydes oxidise readily to form carboxylic acids.
121
What **oxidising reagent** produces a **silver mirror with aldehydes**?
Tollens’ reagent
## Footnote
Aldehydes reduce Ag+ ions to metallic silver.
122
# True or False:
**Ketones** give a **positive** result with **Fehling’s solution**.
False
## Footnote
Only aldehydes reduce Fehling’s solution to form a brick red precipitate.
123
# Fill in the blank:
Reduction of an **aldehyde** forms a _\_\_\_\_\_\_ alcohol.
primary
## Footnote
The carbonyl group is reduced to a hydroxyl group.
124
What type of **alcohol** is formed when a **ketone is reduced**?
Secondary alcohol
## Footnote
The carbonyl carbon becomes bonded to an –OH group.
125
# True or False:
**Aqueous Sodium borohydride** (NaBH4) is used as a **reducing agent** for aldehydes and ketones.
True
## Footnote
It supplies hydride ions for nucleophilic addition.
126
# Fill in the blank:
In **NaBH4 reductions**, the nucleophile that attacks the carbonyl carbon is _\_\_\_\_\_\_.
H-
## Footnote
The hydride ion adds to the carbonyl carbon.
127
What **product** forms when **aldehydes or ketones react with HCN**?
Hydroxynitrile
## Footnote
The CN- ion adds to the carbonyl carbon followed by protonation.
128
Why can **hydroxynitrile formation** from aldehydes produce a **mixture of enantiomers**?
Planar carbonyl group
## Footnote
Nucleophiles can attack from either side of the carbonyl plane.
129
Name the mechanism for the **reduction of aldehydes and ketones to alcohols**.
Nucleophilic addition
130
Name the mechanism for the **reaction of aldehydes and ketones with KCN**.
Nucleophilic additon
131
What are the **conditions** required for the nucleophilic addition of **aldehydes and Ketones with KCN**?
KCN followed by dilute acid
132
What is the main **hazard of potassium cyanide (KCN)**?
It is toxic
133
What is the **general reduction equation for an aldehyde**?
RCHO + [H] → RCH₂OH
134
What is the **general reduction equation for a ketone**?
R₁COR₂ + [H] → R₁CHOHR₂
135
What is the general equation for **formation of a hydroxynitrile from an aldehyde**?
RCHO + HCN → RCH(OH)CN
136
What is the general equation for **formation of a hydroxynitrile from a ketone**?
R₁COR₂ + HCN → R₁C(OH)(CN)R₂
A-Level Chemistry (Edexcel)
flashcards
Decks in class (19)
# Cards
-
Topic 1: Atomic Structure and the Periodic Table72
-
Topic 2: Structure and Bonding90
-
Topic 3: Redox I17
-
Topic 4: Inorganic Chemistry and the Periodic Table90
-
Topic 5: Formulae, Equations and Amount of Substance47
-
Topic 6: Organic Chemistry I127
-
Topic 7: Modern Analytical Techniques I36
-
Topic 8: Energetics I62
-
Topic 9: Kinetics I55
-
Topic 10: Equilibrium I24
-
Topic 11: Equilibrium II12
-
Topic 12: Acid–Base Equilibria69
-
Topic 13: Energetics II27
-
Topic 14: Redox II46
-
Topic 15: Transition Metals134
-
Topic 16: Kinetics II24
-
Topic 17: Organic Chemistry II136
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Topic 18: Organic Chemistry III155
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Topic 19: Modern Analytical Techniques II26
