Syllabus Edition

First teaching 2023

First exams 2025

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Functional Groups: Classification of Organic Compounds (SL IB Chemistry)

Topic Questions

1a1 mark

Define the term hydrocarbon.

1b2 marks

State the general formula for the following hydrocarbon families.

Alkanes …………………………

Alkenes …………………………

1c1 mark

State the IUPAC name of the following hydrocarbon.

10-1-ib-sl-sq-easy-q1c-pent-1-yne

1d3 marks

A student stated that as the number of carbon atoms increases in an alkane, the boiling point increases. State if the student is correct and justify your answer. 

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2a2 marks

Propanal and propanone have the same molecular formula, C3H6O, but have different structures. Draw the displayed structures of propanal and propanone. 

2b1 mark

State the type of isomerism that is exhibited by propanal and propanone.

2c1 mark

Butanone can be reduced to a secondary alcohol by LiAlH4. State the name of this alcohol. 

2d1 mark

State the general formula of an alcohol.

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3a3 marks

Name the three possible isomers of C5H12.

3b1 mark

Using IUPAC rules state the name of the molecule shown in the image below.

10-1-ib-sl-sq-easy-q3b-3d-but-2-ene

3c1 mark

Draw the sterochemical drawing of methane.

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42 marks

Three isomers of pentane are shown below.

1

Give the IUPAC names of isomers B and C.

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5a1 mark

Define the term stereoisomers.

5b2 marks

State the conditions needed for a compound to show cis-trans isomerism.

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1a4 marks

State the IUPAC names for the isomers of C5H12O that are primary alcohols.

1b2 marks

State the IUPAC name for the following primary alcohols.

i)
2-chloro-but-2-en-1-ol-displayed-formula
[1]
ii)
CH2(Br)CH(CH3)CH2OH
[1]

1c1 mark

Draw the displayed formula for a straight chain isomer of CH2(Br)CH(CH3)CH2OH.

1d1 mark

The empirical formula of the compound in part b) i). 

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2a1 mark

Phenacetin is a pain killer though the use of this was banned as it was found to cause harm to kidney function.

10-1-ib-sl-sq-hard-q4a-phenacetin

Deduce the molecular formula of phenacetin. 

2b3 marks

Identify the names of the three functional groups present in phenacetin.

2c1 mark

Aspirin is a common pain killer and has the following structure.

Aspirin
State the empirical formula of aspirin.

2d1 mark

Aspirin is formed from ethanoic anhydride and compound A. State the IUPAC name of compound A.

bb813396-0587-4b67-8460-b5498458cd12

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3a1 mark
Deduce the number of isomers of C6H14

3b2 marks
State the IUPAC name of two branched isomers of C6H14

3c1 mark
Draw the displayed formula of a possible isomer of C6H12 that does not contain a π bond. 

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42 marks

Clenbuterol, shown below, is considered a performance enhancing drug and is believed to increase short term work rate and cardiovascular output.

11-1-ib-sl-sq-hard-q3a-clenbuterol

Deduce the functional groups marked x and y and state to which class they belong to.

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54 marks

Lactic acid has the molecular formula of C3H6O3, and the structural formula of CH3CHOHCOOH.

Illustrate the types of isomerism shown by C3H6O3.

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1a3 marks

Organic compounds are classified into families called a homologous series.

State three features of members belonging to the same homologous series.

1b4 marks

Table 1 shows the boiling points of the first five members of the alkane family.

 Table 1

Alkane

Boiling point/ oC

methane

-162

ethane

-89

propane

-42

butane

-1

pentane

36

 

On the axes below in Figure 1, draw a graph of boiling point against the number of carbon atoms in the alkanes. Estimate the boiling point of the next member of the homologous series, hexane, C6H14, and show on your graph how you arrived at your estimated boiling point. 

Figure 1

10-1-ib-chemistry-sq-q1b-medium

Estimated boiling point of hexane : ________ oC

1c2 marks

State the general formula for an alkyne and give the molecular formula and name of the fifth member of the alkyne family.

1d2 marks

The boiling point of ethyne, C2H2, is -84 oC.

State with, with a reason, whether the boiling point of ethyne would be expected to be higher or lower than the boiling point of ethane, C2H6.

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2a3 marks

Geraniol is a colourless component of rose oil whose structure is shown in Figure 1.

 Figure 110-1-ib-chemistry-sq-q2a-medium

i)
State the names of the two functional groups found in geraniol.
[1]
ii)
Deduce the molecular formula of geraniol. 
[1]
iii)
Draw the displayed formula of geraniol. 
[1]
2b3 marks

Butan-2-ol is an organic compound used industrially to make butanone.

i)
Draw the displayed structure of butan-2-ol. 
[1]
ii)
Draw the displayed structures of a positional isomer and a functional group isomer of butan-2-ol.
[2]
2c2 marks

Draw and name all the branched-chain isomers of butan-2-ol.

2d1 mark

State, with a reason, the class of alcohols which butan-2-ol belongs to.

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3a2 marks

The formulae of four organic compounds are given in Table 1. Write the names of the compounds in the second column.

Table 1

compound

name

CH3CH2CH2CH(OH)CH3

 

CH3CH2COCH3

 

CH3CH2CH2OH

 

CH3CH2CH2CHO

 

3b2 marks

Which of the compounds in part (a) are structural isomers of each other and what type of isomerism do they show?

3c3 marks

Propofol is a drug used to reduce consciousness during medical procedures. The skeletal structure of propofol is given in Figure 1.

Figure 1

10-1-ib-chemistry-sq-q3c-medium

i)
Determine the empirical formula of propofol. 
[1]
ii)
Identify the number of positional isomers of propofol (not including propofol). 
[1]
iii)
State the names of two functional groups found in propofol.      
[1]
3d3 marks

Valeric acid, C5H10O2, is a straight chain carboxylic acid found in the plant Valeriana officinalis.

i)
State the general formula for a carboxylic acid.
[1]
ii)
Give the systematic name for valeric acid. 
[1]
iii)
Draw a condensed structural formula for valeric acid.
[1]

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4a5 marks

Draw and name all the possible isomers of C6H14.

4b2 marks

Figure 1 below shows a three-dimensional structure of a molecule.                                                  

Figure 110-1-ib-chemistry-sq-q4b-medium 

i)
Using IUPAC rules state the name of this molecule. 
[1]
ii)
Draw and name a functional group isomer of this molecule. 
[1]

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5a1 mark

Toluene is a common organic chemical with many industrial and commercial applications. Toluene is also known as methylbenzene. 

Draw the molecular structure of toluene.  

5b2 marks

Another derivative of benzene has the molecular formula C8H10. 

Draw the structures of the four possible isomers of this derivative.

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6a1 mark

The analytical instruments used for identification of organic compounds are constantly being improved.            

 Mass spectroscopy is one such analytical tool which provides key information used to identify an unknown compound. 

An unknown compound has the empirical formula C2H4O, and its mass spectrum has a molecular ion peak at m/z 84.

Deduce the molecular formula of the compound.  

6b2 marks

The unknown compound is a carboxylic acid. Deduce the two possible carboxylic acid structural isomers.  

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73 marks

A group of students are asked to distinguish between four samples of different organic compounds.            

The four samples are as follows: 

  • A primary alcohol 
  • A tertiary alcohol 
  • An aldehyde 
  • A carboxylic acid

Describe how the group of students could distinguish between the two different alcohols.

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8a2 marks

A molecule of oleic acid is shown.q1a_20-3_ib_hl_medium_sq

Oleic acid is a fatty acid which occurs naturally in different animals and plants.

Oleic acid exhibits stereoisomerism. Explain the meaning of this term and identify why oleic acid has stereoisomers.

8b4 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.

[1]

ii)
Crotonic acid has a carboxylic acid functional group. Draw the displayed formula of the positional and branch-chain isomers of crotonic acid.
[2]
iii)
Identify which of the isomers you have drawn shows E / Z isomerism.
[1]

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9a4 marks

A chemist is analysing a collection of organic compounds. The structural formulae of these compounds are shown.ma2a_20-3_ib_hl_medium_sq

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

9b5 marks

This question refers to the compounds in the table in part (a)

i)
Identify the compounds which have chain isomers and draw their isomers.
[3] 
ii)
State the empirical formula of compound 3. 
[1]
iii)
Does compound 4 exhibit stereoisomerism? Explain your answer.
[1]

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102 marks

2-methylbut-2-ene can be converted into 2-methylbutan-2-ol, a liquid that smells of camphor. 

State the reagents needed to convert 2-methylbut-2-ene into 2-methylbutan-2-ol.

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11a1 mark

Dichloroethene exists as two stereoisomers. Draw the structures of these isomers. 

11b1 mark

Explain why dichloroethene has stereoisomers.

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