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Formulae, Functional Groups & Terminology (CIE IGCSE Chemistry: Co-ordinated Sciences (Double Award))

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Formulae, Functional Groups & Terminology

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Formulae, Functional Groups & Terminology

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11 mark

The diagrams show part of the structures of five substances, A, B, C, D and E.

dFPHIipH_q1-0620_s19_qp_32

Which one of these structures, A, B, C, D or E is an alcohol?

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21 mark

The structure of nerol is shown below:

q7_0620-s20-qp-32_cie-igcse-chemistry

Draw a circle around the alcohol functional group in nerol.

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31 mark

The structure of nerol is shown.

i5ablJmz_q7_0620-s20-qp-32_cie-igcse-chemistry

What feature of the nerol molecule shows that it is an unsaturated compound?

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41 mark

Sulfur dioxide, SO2, is used in the manufacture of sulfuric acid.

When propan-1-ol is heated with concentrated sulfuric acid as a catalyst an unsaturated hydrocarbon of relative molecular mass 42 is formed and one other product.

What is meant by the term unsaturated?

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5a1 mark

Coal gas is made by heating coal in the absence of air.
The list shows the main gases present in coal gas.

carbon dioxide
carbon monoxide
ethene
hydrogen
methane
nitrogen

Which one of these gases is an alkane?

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5b1 mark

Draw the structure of a molecule of ethene. Show all of the atoms and all of the bonds.

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6a1 mark

Methane, ethane and ethene are hydrocarbons.

Draw the structure of a molecule of ethane. Show all of the atoms and all of the bonds.

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6b1 mark

Which one of these compounds belongs to the same homologous series as methane?

Draw a circle around the correct answer.


butane                    methanoic acid                    methanol              propene

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6c1 mark

The structure of a monomer used to make a polymer is shown.

q5f-0620_s19_qp_32

What structural feature of this molecule shows that it is unsaturated?

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6d2 marks

Describe a test to show that this compound is unsaturated.

test                     ....................................................

observations     ....................................................

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1a1 mark

The structures of six organic compounds are shown.

6-compounds-cie-igcse

Give the name of F.

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1b2 marks

Separate: Chemistry Only

Identify two of the compounds that are members of the same homologous series.

Give the general formula of this homologous series.

compounds ..................................................

general formula ..................................................

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1c2 marks

Explain why B is an unsaturated hydrocarbon.

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1d3 marks

Extended tier only

Describe how D is manufactured from B. Give a chemical equation for the reaction.

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1e2 marks

Extended tier only

Compound A forms an addition polymer.

Draw two repeat units of the addition polymer formed from A.

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2a3 marks

Alkenes can be made from alkanes by cracking.

 
i)
Explain the term cracking.
 
[2]
 
ii)
One mole of an alkane, when cracked, produced one mole of hexane, C6H14, and two moles of ethene.
 
What is the molecular formula of the original alkane?
 
[1]

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2b5 marks

Extended tier only

Alkenes are used in polymerisation reactions and addition reactions.

 
i)
Draw the displayed formula of the product formed by the addition polymerisation of but-2-ene. Its formula is given below.
 
but-2-ene-exam-q-structure
 
[3]
 
ii)
Give the name and displayed formula of the addition product formed from ethene and bromine.
 
name ..............................................................
 
displayed formula ..............................................................
 
[2]

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3a3 marks

Extended tier only

The alcohols form a homologous series. The first five members are given in the table below.

 
alcohol formula heat of combustion in kJ / mol
methanol  CH3OH  730
ethanol  CH3–CH2–OH  1380
propan-1-ol    
butan-1-ol  CH3–CH2–CH2–CH2–OH 2680
pentan-1-ol  CH3–CH2–CH2–CH2–CH2–OH 3350
 
i)
Complete the table. 
 
[2]
 
ii)
Complete the equation for the combustion of pentan-1-ol in excess oxygen.
 
C5H11OH + .......O2 → ..................... + .....................
 
[1]

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3b3 marks

Extended tier only

State three characteristics of a homologous series other than the variation of physical properties down the series.

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4a7 marks

Extended tier only

Two homologous series of hydrocarbons are the alkanes and the alkenes.

One general characteristic of a homologous series is that the physical properties vary in a predictable way.

 
i)
State three other general characteristics of a homologous series.
 
[3]
 
ii)
How can the molecular formula of a hydrocarbon show whether it is an alkane or an alkene?
 
[2]
 
iii)
How do alkanes and alkenes differ in their molecular structures?
 
[2]

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4b5 marks

Cracking is the thermal decomposition of alkanes into smaller hydrocarbons and possibly hydrogen.

 
i)
State two conditions required for the cracking of an alkane.
 
[2]
 
ii)
One type of cracking produces an alkane and an alkene.
 
Complete an equation for the cracking of heptane into an alkane and an alkene.
 
C7H16 → ................ + ................
 
[1]
 
iii)
Complete an equation for the cracking of heptane into hydrogen and two other products.
 
C7H16 → ................ + ................ + H2
 
[1]
 
iv)
Suggest one reason why cracking is important.
 
[1]

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5a2 marks

Petrol is a mixture of hydrocarbons and additives. The combustion of petrol in car engines is a major source of air pollution. This is reduced by catalytic converters.

Petrol is obtained from the gasoline fraction, boiling point range 40 °C to 100 °C, from the distillation of petroleum.

Explain the term fraction.

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5b6 marks

Extended tier only

In many countries, a lead compound of the type Pb(C2H5)n used to be added to petrol to improve its combustion. After combustion, lead oxide was formed.

 
petrol-pump
 
i)
Octane is a constituent of petrol. Write the equation for the complete combustion of octane.
 
C8H18 + .......... O2 → .......... + ..........
 
[2]
 
ii)
Dibromoethane was added to petrol to remove the lead oxide from inside the engine. Lead bromide was formed which escaped into the environment through the exhaust. Leaded petrol cannot be used with a catalytic converter.
 
Give another reason why leaded petrol is no longer used.
 
[1]
 
iii)
What does each of the following tell you about the structure of dibromoethane?
 
dibromo ......................................................................................................................
 
eth ..............................................................................................................................
 
ane .......................................................................................................................
 
[2]
 

iv)
What additional information is needed to draw the structural formula of dibromoethane?
 
[1]

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5c2 marks

Extended tier only

An analysis of the compound, Pb(C2H5)n, showed that 0.026 moles of Pb was combined with 0.104 moles of C2H5 groups.

What is the value of n? Show how you arrived at your answer.

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5d3 marks

Extended tier only

Some of the pollutants emitted by vehicle exhausts are carbon monoxide, oxides of nitrogen and unburnt hydrocarbons. Explain how the emission of these gases is reduced by a catalytic converter.

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6a2 marks

Alkynes and alkenes are homologous series of unsaturated hydrocarbons.
All alkynes contain a C≡C triple bond.

Complete Table 10.1 showing information about the first three alkynes.


Table 10.1

formula straight C subscript 2 straight H subscript 2 straight C subscript 3 straight H subscript 4  
structure straight H minus straight C identical to straight C minus CH subscript 3 straight H minus straight C identical to straight C minus CH subscript 2 minus CH subscript 3
names ethyne   but-1-yne

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6b2 marks

Extended tier only

Compounds in the same homologous series have the same general formula.

Give two other characteristics of members of a homologous series.

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6c2 marks

Alkynes are unsaturated.
Describe a test for unsaturation.
test   ........................

result ........................ 

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6d2 marks

Ethene and but-2-ene are alkenes.

Draw the displayed formula of but-2-ene.

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6e2 marks

Draw a dot-and-cross diagram to show a molecule of ethene, CH2=CH2.

Show outer shell electrons only.

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7a3 marks

There are three functional groups in compound A.

q6c-0620-s20-qp-42

Name the homologous series of compounds that contains the following structures.

C=C       ...............................
–OH       ..............................
–COOH ...............................

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7b2 marks

Extended tier only

Compound A can be used as a single monomer to produce two different polymers.

Draw one repeat unit of the addition polymer formed from compound A.

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8a1 mark

The structures of five alkenes, A, B, C, D and E, are shown.

q5-0620_s19_qp_41

What is the general formula of alkenes?

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8b2 marks

Extended tier only

Two different alcohols can be produced from alkene B by an addition reaction.

q5f-0620_s19_qp_41

Draw the structures of the two alcohols. Show all of the atoms and all of the bonds.

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9a1 mark

The structure of myrcene is shown.

q7_0620-s20-qp-31_cie-igcse-chemistry

Deduce the formula of myrcene to show the number of atoms of carbon and hydrogen.

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9b3 marks

Myrcene is an unsaturated hydrocarbon.

Describe a chemical test to distinguish between a saturated and an unsaturated hydrocarbon.

test ...................................
observations with saturated hydrocarbon .............................................
observations with unsaturated hydrocarbon .........................................

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9c1 mark

Butane is a saturated hydrocarbon.

To which homologous series does butane belong?

Draw a circle around the correct answer.

alcohol                    alkane                   alkene                   carboxylic acid

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1a3 marks

Alkanes and alkenes are examples of hydrocarbons.

i)
What is meant by the term hydrocarbon?

[1]

ii)
Give the general formula of straight-chain

alkanes.

alkenes. 
[2]

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1b4 marks

Extended tier only

A polyester is represented by the structure shown.

polyester-structure

i)
What type of polymerisation is used for the production of polyesters?

[1]

ii)
Which simple molecule is removed when the polyester is formed?

[1]

iii)
Complete the diagrams below to show the structures of the monomers used to produce the polyester. Show all atoms and bonds.
polyester-monomers

[2]

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21 mark

Propanoic acid is a carboxylic acid. Its formula is CH3–CH2–COOH.

Propanoic acid is the third member of the homologous series of carboxylic acids.

Name the fourth member of this series.

 

   name ...............................................................

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3a
Sme Calculator4 marks

Extended tier only

The alcohols form a homologous series. The first member is methanol and the fourth is butanol.

CH3–OH
methanol		 CH3–CH2–CH2–CH2–OH
butanol

i)
Give two general characteristics of a homologous series.
 
[2]
 
ii)
Calculate the mass of one mole of the C8 alcohol.
 
[2]

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3b2 marks

Give the name and displayed formula of the third member of this series.

 
name ..................................................
 
[1]
 
displayed formula ..................................................
 
[1]

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42 marks

Extended tier only

Butane is an alkane. It has the following structural formula

Butane Displayed Formula

The equation for the complete combustion of butane is given below. Insert the two missing volumes.

 
  2C4H10 (g)  + 13O2 (g)  → 8CO2 (g)  + 10H2O (g)
volume of gas / cm3 ..........  ..........  40  
 

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