Introduction to Organic Chemistry (AQA A Level Chemistry)

Exam Questions

4 hours45 questions
1a3 marks

Hexane and octane are part of the alkane homologous series.

i)
Define the term homologous series.

ii)

Give the general formula for the homologous series of alkanes.

1b4 marks

A chemist is analysing some organic compounds. The structural formulae of these compounds are shown in Table 1.

Table 1

1-4

Give the IUPAC names for the following molecules shown in Table 1.

1c2 marks

The compound 2,2-dimethylpentan-3-ol can be represented using different types of formula. Its structural formula can be shown as C(CH3)3CH(OH)CH2CH3.

i)
Give the empirical formula of 2,2,dimethylpentan-3-ol.

ii)
Draw the skeletal formula of 2,2,dimethylpentan-3-ol.
1d2 marks

Dodecane is part of the alkane homologous series.

State two characteristics of a homologous series.

Did this page help you?

2a5 marks

Some organic molecules can be classified as aliphatic molecules.

i)
Describe the structural difference between aliphatic and aromatic organic molecules.

ii)
Give the IUPAC names for the following aliphatic molecules in Table 1.

Table 1

Aliphatic molecule

IUPAC name

CH₃CH₂CH₂OH

 

CH₃CH₂CH=CH₂

 

CH₃CH(CH3)CH(CH3)CH₂CH₂CH₃

 

CH₃CH₂CHCICH₂OH

 

2b2 marks

This question is about different alkanes present in crude oil.

Compound Y, shown in Figure 1 below, is one of the structural isomers of C7H16.

Figure 1

yQ9nVfAy_2-3

i)
What is meant by the term structural isomers.

ii)
Give the IUPAC name for compound Y in Figure 1.
2c4 marks

Organic molecules can be drawn using the skeletal formula.

Complete Table 2 below to show the skeletal formulas of the following organic molecules.

Table 2

Organic molecule

Skeletal Formula

1,1-dibromo-2,2-dichloroethane

 

1,2-dibromo-1,2-dichloroethane

 

1,1,1-triiodoethane

 

CCl3CH2CHBrCH2Cl

 

2d4 marks

Hexane, C6H14 exists as 5 chain isomers. The structural formula of hexane is CH3CH2CH2CH2CH2CH3.

Write the structural formula of the other four chain isomers of hexane and state their IUPAC names.

Did this page help you?

3a2 marks

Propanol, C3H7OH, is a member of the homologous series of alcohols.

Draw the skeletal formula for the position isomers of propanol and state the IUPAC name for each isomer.

3b3 marks

Tollens’ reagent can be used to distinguish between an aldehyde and ketone. Propanal, CH3CH2CHO, and propanone, CH3COCH3, are functional group isomers.

i)
Explain why propanal and propanone are functional group isomers.

ii)

State any observations with the use of Tollens’ reagent to distinguish between propanal and propanone.

3c1 mark

Figure 1 shows the skeletal formula of four alcohols, W, X, Y and Z.

Figure 1

3-1

State which pair of alcohols are structural isomers of each other.

A - W and X

B - W and Y

C - W and Z

D - X and Y

3d3 marks

The structures in Figure 2 show two naturally occurring alcohols.

Figure 2

5o1lJEBY_4-1

i)
State what is meant by the term unsaturated.

ii)
Give the molecular formula of these two alcohols.

Did this page help you?

4a4 marks

Pent-2-ene is an example of a stereoisomer.

i)
Define the term stereoisomer.

ii)

Draw the structural formulae for the E and Z stereoisomer of pent-2-ene.

4b2 marks

2-bromo-1-chloropropene is a colourless, odourless liquid.

A student drew the two stereoisomers of 2-bromo-1-chloropropene below in Figure 1.

Figure 1

suqbsScv_5-1

State what is incorrect with their diagrams of these two stereoisomers.

4c2 marks

Methylcyclohexane is a saturated hydrocarbon which has uses as a solvent.

i)
State the meaning of the term saturated.

ii)
Draw the skeletal formula of methylcyclohexane.
4d2 marks

A student stated that cyclohexane is an aromatic molecule which is a functional group isomer of hex-1-ene.

State and explain if you agree with the students statement.

Did this page help you?

5a2 marks

Menthone is a cyclic molecule that can be used in essential oils as it gives a peppermint aroma.

Figure 1

nRlU5HYz_6

State the molecular and empirical formula of menthone.

5b2 marks

Some organic molecules exhibit stereoisomerism. Stereoisomers are compounds that have the same atoms connected to each other, however the atoms are differently arranged in space.

Draw the E and Z stereoisomers for 2,3-dichlorobut-2-ene.

5c3 marks

Table 1 shows the IUPAC names of three compounds with an Mr of 86.0.

Table 1

IUPAC name

Skeletal formula

Structural Formula

Pentanal

 

 

Hexane

 

 

Pentan-2-one

 

 


Complete Table 1 to show the skeletal and structural formulas of the three molecules.

5d3 marks

The organic compounds in Table 2 below can be termed, aliphatic, alicyclic or aromatic.

Table 2

3_ZH2uMx_7

Identify, using letters E, F, G, H, I, J, the compound(s) which are the following types.

Each response may contain more than one letter.

  • Aliphatic
  • Alicyclic
  • Aromatic

Did this page help you?

1a3 marks

Oleic acid is a fatty acid which occurs naturally in different animals and plants. It is also widely produced in industry, for its uses as an emulsifying agent and in the pharmaceutical industry. Figure 1 shows the structure of oleic acid.

Figure 1

1-6

i)
State the type of formula oleic acid is represented by in Figure 1.

ii)
Deduce the molecular formula of oleic acid.

iii)
Draw the displayed formula of oleic acid. 
1b4 marks

Oleic acid displays stereoisomerism. Figure 1 in part (a) shows one of the stereoisomers that oleic acid can exist as.

i)
Define the term stereoisomerism.

ii)
Apply the CIP priority rules to draw the skeletal formula of the second stereoisomer.

iii)

Figure 2 below shows another fatty acid which is commonly found in milk. Explain why this compound does not display stereoisomerism.

Figure 2

2-5

1c4 marks

Crotonic acid is another fatty acid which has a similar structure to oleic acid. The molecular formula of crotonic acid is C4H6O2.

i)
State the empirical formula of crotonic acid.

ii)
Crotonic acid has a carboxylic acid functional group. Draw the displayed formula of the position and chain isomers of crotonic acid.

iii)
Draw the cyclic functional group isomer of crotonic.
1d4 marks

Two students, Student A and Student B, discuss the properties of oleic acid and crotonic acid.

Student A claims that both compounds belong to the same homologous series and Student B claims that both compounds have similar chemical properties.

Are either of the students correct? Explain your answer.

Did this page help you?

2a3 marks

Crude oil consists of a mixture of hydrocarbons, which can be separated by fractional distillation. The shorter hydrocarbons are more useful as fuels such as gasoline and diesel fuel, so longer hydrocarbons are often converted into shorter ones in a       process called cracking. Cracking of hydrocarbons results in the formation of shorter alkanes and alkenes.

A hydrocarbon with molecular formula C12H24 is cracked to form oct-1-ene and one other alkene.

i)
Write an equation for this cracking reaction.

ii)
Draw the displayed formula of the functional group isomer and the position isomer of the second alkene formed in this reaction.
2b4 marks

Figure 1 shows the reaction mechanism by which butene reacts with hydrogen bromide, to form compound X.

Figure 1

kxajo8DZ_3-3

i)
What does the curly arrow going from the C=C bond to the H in H-Br represent?

ii)
State and explain the errors in the mechanism shown in Figure 1.

iii)
Give the IUPAC name of compound X.
2c6 marks

Compound X can also be formed from the reaction of butane with bromine.

CH3CH2CH2CH3 + Br2 → CH3CH2CHBrCH3 + HBr

i)
State what type of reaction this is and the type of bond fission involved. 

ii)
State which condition is required for the initiation step of this reaction.

iii)
Write the equations for each of the following steps in the reaction of butane with bromine. There are multiple equations for the termination step, however only write the one that shows the formation of CH3CH2CHBrCH3

Initiation step:                                                                 

Propagation step:                                        

Termination step: 

2d3 marks

Once bromobutane has formed, further substitution can occur to form a compound with empirical formula C2H4Br.

Draw all the structural isomers of this compound.

Did this page help you?

3a4 marks

A chemist is analysing a collection of organic compounds. The structural formulae of these compounds are shown in Table 1 below.

Table 1

table

Give the IUPAC name for the compounds to complete the table.

3b7 marks

The scientist carried out some analytical research on his collection of compounds and found that some of these compounds display isomerism.

i)
Identify the compounds which display chain isomerism and draw their isomers.

ii)
State the empirical formula of compound 3.

iii)
Does compound 4 exhibit stereoisomerism? Explain your answer.
3c7 marks

The scientist carries out a synthetic reaction to form compound D from compound A as shown in the reaction sequence in Figure 1 below.

Figure 1

5-3

i)
State the IUPAC names for compounds A-D

ii)
Draw curly arrows in Figure 2 below to complete the mechanism for reaction 2.

Figure 2

6-2
iii)
Draw all of the chain isomers of compound C while keeping the cyanide (CN) group in the same position.
3d2 marks

Another compound in the scientist’s collection of organic compounds is shown in Figure 3 below.

Figure 3

7-2

This compound is the Z isomer. Which one of the labelled bonds leads to the prefix Z in the name? Explain your answer using CIP rules.

Did this page help you?

4a2 marks

Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They are widely used as solvents for dry cleaning, as refrigerants and as propellants for aerosols. 1,1,1,2,2-pentachloro-2-fluoroethane (CFC X) is an example of such CFCs.

Figure 1

EWUIoBPt_8-1

State the IUPAC names of CFC Y and Z shown in Figure 1.

4b6 marks

Unfortunately, CFCs are largely responsible for destroying the ozone layer. In the high atmosphere, the carbon-chlorine bonds break to give chlorine free radicals. It is these radicals which break down the O3 and destroy the ozone layer. Figure 2 below shows the mechanism for this reaction.

Figure 2

75GS1R51_9-1

i)
State the type of reaction shown in Figure 2.

ii)
The reaction in part (i) consists of three processes. Label each of the individual reactions in Figure 2 with the name of the correct process.

iii)
State the error in the mechanism shown in Figure 2 and state the essential conditions needed for this reaction.
4c5 marks

CFCs are now being replaced by less environmentally harmful compounds such as hydrofluorocarbons (HFCs). These compounds only contain hydrogen, carbon and fluorine atoms. Since they don’t contain a chlorine atom, they have no effect on the ozone layer.

An example of a HFC is a compound with molecular formula C3H5F3.

Draw all the possible structural isomers of this compound.

4d7 marks

Amines are often used in making azo-dyes and nylon apart from medicines and drugs.

Draw the skeletal formula for 4-bromo-5,6-dimethylheptan-2-amine.

Did this page help you?

5a3 marks

This question is about the structure of organic compounds.

i)
Draw the displayed formula of 2,3-dimethylpentanal.

ii)
Draw the skeletal formula of compound X formed in Figure 1.
axiPzsyj_10-1

iii)
State the empirical formula of the monochloro product formed in the free-radical substitution reaction between propane and chlorine.
5b6 marks

Figure 2 shows the displayed formula of a type of fuel known as gasoline.

i)

Give the IUPAC name of the compound shown in Figure 2.

Figure 2
kAU2gUrf_11

ii)
State the number of monochloro isomers which would be possible for the molecule in Figure 2.

iii)

Draw the skeletal formulae of these monochloro isomers. Don't include chain isomers but only move the position of the chlorine atom.

5c4 marks

Pent-1-ene (C5H10) is a member of the homologous series of alkenes. Pent-1-ene has structural isomers but no stereoisomers.

i)
Define the term structural isomerism. 

ii)
Give the IUPAC names of all possible functional group isomers of pent-1-ene.

iii)
Draw the skeletal formula of the position isomers of pent-1-ene.
5d3 marks

The structure of an alcohol X is shown in Figure 3.

Figure 3

Yvm3TiEt_12

i)

Give the IUPAC name for alcohol X.

ii)
What is the general formula of the homologous series of alcohols, which contain only one -OH group per molecule?

iii)
State the empirical formula of alcohol X.

Did this page help you?

1a3 marks

The characteristic smell of pine wood is due, partly, to the presence of a group of compounds called terpenes. One of the simpler terpenes is a compound called geraniol, which is an oily liquid at room temperature and pressure. The structure of geraniol is shown in Figure 1.

Figure 1

1-5

i)
Deduce the molecular formula of geraniol. Use your answer to calculate the molar mass of geraniol in g mol−1.

ii)

Draw the displayed formula of geraniol.

1b6 marks

Figure 2 shows the displayed formula of a type of fuel. 

i)
Give the IUPAC name of the compound shown in Figure 2.

Figure 2

2-4
ii)
State the number of monochloro isomers which would be possible for the molecule in Figure 2

iii)
Draw the skeletal formulae of these monochloro isomers. Don’t include chain isomers but only move the position of the chlorine atom.
1c7 marks

A compound with a molar mass of 72.0 g mol-1 is composed of 66.63% C, 11.18% H, and 22.19% O.

i)
How many structural isomers can this compound form, which contain a carbon-oxygen double bond.

ii)

Draw and name the skeletal formula of these isomers.

1d7 marks

1,1,1,2-tetrafluoro-but-2-ene is another compound containing hydrogen, carbon and fluorine atoms.

i)
State the meaning of the term stereoisomers and explain why 1,1,1,2-tetrafluoro-but-2-ene displays stereoisomerism. 

ii)
Draw the E and Z isomers of 1,1,1,2-tetrafluoro-but-2-ene.

Did this page help you?

2a2 marks

Ethers are a homologous series of organic compounds containing the R−O−R functional group.

The structures and names of two ethers are shown in Figure 1.

Figure 1

8fSlncjb_3-2

i)
Draw the skeletal formula of the ether, 2-ethoxy-3-methylbutane.

ii)
Determine the molar mass of 2-ethoxy-3-methylbutane.
2b1 mark

Ethers can be prepared by nucleophilic substitution of haloalkanes with alkoxide ions, RO.

Alkoxide ions can be prepared by reacting sodium with an alcohol. A gas is also formed.

Write an equation for the formation of methoxide ions from sodium and an alcohol.

2c3 marks

Methoxyethane, shown in part (a), can be prepared by reacting bromoethane, CH3CH2Br, with methoxide ions, CH3O.

Outline the mechanism for the nucleophilic substitution of CH3CH2Br with CH3O using skeletal formulae.

Your answer should include relevant charges, dipoles and the products formed.

2d2 marks
i)
In this mechanism, explain how CH3O ions have acted as a nucleophile.

ii)

A student commented that this is an example of homolytic fission. Using your knowledge of organic mechanisms, justify this statement.

Did this page help you?

3a4 marks

Cisplatin is an effective intravenous anti-cancer drug. It exists in two stereoisomers cisplatin and transplatin, only cisplatin is effective as a chemotherapy treatment. Cisplatin exists as a square planar molecule with a platinum (Pd2+) central metal ion surrounded by two NH3 and two Cl- ions which act as ligands. Each ligand forms a coordinate bond with the platinum ion.

i)
Draw the 3D representation of cisplatin including the bond angles.

ii)
State the limitation of the cis-trans naming rules when it comes to the molecule shown in Figure 1.
OMwqpp3-_4-2
iii)
State the name of the molecule shown in Figure 1.
3b2 marks

This question is about saturated hydrocarbons. Compound A is shown in Figure 2.

Figure 2 

54

The reaction of compound A with excess chlorine forms a compound D, which has a molar mass of 175.5 g mol−1.

Draw a possible structure for compound D and write the equation for its formation from compound A. Use molecular formulae in the equation.

3c3 marks

Butenedioic acid is HOOCCH=CHCOOH. It has two stereoisomers, commonly known as malic acid and fumaric acid. Both acids are responsible for the sour taste in fruit.

i)
Draw the two E-Z isomers of butenedioic acid in skeletal formulae and label them as E-butenedioic acid and Z-butenedioic acid.

ii)
State which part or parts of the molecule are responsible for the sour fruit taste. 
3d7 marks

The hydrocarbon propane can be reacted with chlorine to prepare 2-chloropropane, CH3CHClCH3, by free radical substitution.

i)
Write the overall equation and state the conditions for this reaction.

ii)
Outline the mechanism by naming and providing relevant equations for each step in the formation of 2-chloropropane.

iii)
Describe the limitations of this method of preparation.

Did this page help you?

4a3 marks

A student named the alcohol molecule shown in Figure 1 as Z-1,4-dichlorohex-2-ene-6-ol.

Figure 1

6-1

State the errors the student has made in naming the molecule and give the correct IUPAC name.

4b3 marks

Aspirin is an ester of salicylic acid, HOC6H4CO2. Aspirin is formed when an ester bond is created between the salicylic acids OH group and ethanoic anhydride, (CH3CO)2O, in the presence of an acid catalyst, as shown in Figure 2. Ethanoic acid is also formed as a product.

Figure 2

78

i)
Draw the skeletal formulae for both products of this reaction.

ii)
Determine the molar mass of aspirin.
4c3 marks

The organic compounds in Figure 3 below can be termed aliphatic, alicyclic or aromatic.

Figure 3 

Fk2kh56k_8

Each response may contain more than one letter for the questions below.

i)
Identify, using letters E, F, G, H, I, J, the compound(s) which are aliphatic.

ii)
Identify, using letters E, F, G, H, I, J, the compound(s) which are alicyclic.

iii)
Identify, using letters E, F, G, H, I, J, the compound(s) which are aromatic.
4d4 marks
i)
Using Figure 3 in part (c), state which compound E, F, G, H, I, J can be categorised as aliphatic but not alicyclic.
Justify your answer.

ii)
Describe a simple test that the student could carry out to confirm the presence of the functional group in compound H.
Draw the structure of the organic product from the test.

Did this page help you?

5a2 marks

Compounds with a carbon−carbon double bond are unsaturated. Figure 1 shows an unsaturated hydrocarbon.

Figure 1

wIIX68r-_9

i)
Name the isomer shown in Figure 1.

ii)
Justify the CIP naming rule for this isomer.
5b2 marks

Two structural isomers of C10H18O are linalool and geraniol. They are unsaturated alcohols with similar chemical properties and are both used in perfumes.

The IUPAC names for both linalool and geraniol are shown in Table 1.

Table 1

Isomer

IUPAC name

Linalool

3,7-dimethylocta-1,6-dien-3-ol

Geraniol

3,7-dimethylocta-2,6-dien-1-ol

Draw the skeletal formulae for these two isomeric alcohols.

5c3 marks

The organic compounds below in Figure 2 are all made by living organisms.

Figure 2

AJ4NxPsN_10

i)
State the IUPAC name for compound A.

ii)

Compound D reacts readily with hydrogen chloride in an addition reaction. Two products are formed in this reaction, but one of the products is formed in much greater amounts than the other.
Draw the structures of both possible addition products of this reaction.

5d3 marks

4.125 g of compound D (from part C) is reacted with an excess of hydrogen chloride. The mixture of products contains 95% by mass of one product and 5% by mass of the other product.

Calculate the mass of each product formed.

Did this page help you?