Unit 2

National 5 Chemistry
Exam Revision
Nature’s Chemistry
Definitions
Define the following terms;
a)
b)
c)
d)
e)
f)
Fuel
Homologous series
Isomer
Addition reaction
Hydrocarbon
Combustion
Definitions
Define the following terms;
a) Cracking
b) Saturated
c) Unsaturated
Fuels
When a hydrocarbon is burnt, carbon dioxide and
water are produced. The following experiment can
be used to investigate the products of combustion.
Complete the diagram to show the
apparatus which would be used to
collect the water.
Candle wax is a hydrocarbon. Blue cobalt chloride
paper and limewater can be used to detect products
formed when candle wax is burned.
a) Complete and label the diagram to show the
arrangement you would use.
b) Name the product detected using the blue cobalt
chloride paper.
c) As the candle burns the funnel becomes coated with
soot.Why does this happen?
Homologous Series
Write the general formula for the;
a)
b)
c)
d)
Alkanes
Alkenes
Cycloalkanes
Alkanoic acids
Which of the following compounds belongs to the same
homologous series as the compound with the molecular
formula C3H8?
1. A very hot flame is produced when ethyne gas
(C2H2) burns in a plentiful supply of oxygen.
a) Name the products formed in this reaction.
b) Ethyne is the first member of an homologous series
called alkynes. Ethyne has the following structure.
All the members of the alkyne series have a triple
carbon to carbon bond. Complete the table below.
Position in
series
1st
2nd
3rd
Name
Ethyne
Butyne
Molecular
formula
C2H2
C3H4
Isomers
Which of the following is an isomer
of the compound shown in the red
box?
Are these compounds isomers?
Are these compounds isomers?
Are these compounds isomers?
Addition Reactions
Draw the full structural formula for the product
formed by the reaction of bromine with each of the
following hydrocarbons.
a)
b) but-2-ene
c)
Cracking
The diagram shows how paraffin, C12H26 , can be
cracked.
a) Name the catalyst used in cracking.
One of the reactions taking place when paraffin is cracked is
b) Identify molecule X.
c) Describe what would be seen when X
is added to bromine solution.
Identify X
a) C8H18

C4H10
+
X
b) C6H14

C3H6
+
X
c) C12H26

C6H14
+
X
d) C10H22

C6H12
+
X
e) C7H16

C2H6
+
X
Systematic Naming
Name the following;
1.
3.
2.
4.
Name the following:
5.
6.
7.
8.
Name the following:
9.
10.
11.
12.
Drawing full
structural formula
Draw the full structural formula for;
a)
b)
c)
d)
e)
f)
g)
h)
i)
Hexane
Cyclobutane
The first member of the alkenes
The first member of the cycloalkanes
Ethanoic acid
Propan-2-ol
2,3-dimethylbutane
2-methylbut-1-ene
Pent-1-ene
Draw the full structural formula for:
a)
b)
c)
d)
e)
f)
g)
h)
3-ethyl pentanoic acid
2,2 dimethypentan-1-ol
CH2CHCH2CH3
3,3-dimethyl hexanoic acid
3methylbutan-1-ol
2-methylhexan-3-ol
CH2CH2
2,4-dimethylpentane
Functional Groups
Which functional group is found in the
following;
a)
b)
c)
d)
Alkenes
Alkanols
Alkanoic acids
Esters
a) Linalyl ethanoate is made from an alcohol and
ethanoic acid. To which group of compounds
does linalyl ethanoate belong?
b) Identify the hydroxyl group
Methylpropene and an alkane can be use to produce
2,2,4-trimethylpentane, a molecule added to petrol.
a)
Give the systematic name for the alkane used to
produce 2,2,4-trimethylpentane.
b)
Name the type of chemical reaction shown above.
The dehydration of ethanol
to ethane was carried out
using the following
apparatus.
1. Complete the word equation for the reaction
Ethanol

Ethene + ___________________
2. As a safety precaution, the delivery tube was removed
from the water before heating was stopped. Why?
3. Why is the aluminium oxide catalyst described as being
heterogeneous?
4. What would the mass of aluminium
oxide catalyst be after the reaction was
complete?
Esters
Name the ester formed between:
a)
b)
c)
d)
e)
f)
Methanoic acid and methanol
Propanoic acid and ethanol
Ethanol and methanoic acid
Propanol and butanoic acid
Pentanol and methanoic acid
Butanoic acid and methanol
Uses of Carbon
Compounds
Uses of Carbon Compounds
a) Why can ethanol be described as a
renewable source of energy?
b) State a use of an ester
c) State a use of an alcohol
d) State a use of a carboxylic acid
Energy from Fuels
Calculate Eh from each set of results
a) The temperature of 50 cm3 of water is
increased by 12 oC.
b) The temperature of 250 cm3 of water
increases from 21.8 oC to 27.9 oC.
c) The temperature of 1000 cm3 of water
increases from 8.4 oC to 19.4 oC.
d) The temperature of 1cm3 of water
is increased by 20.5 oC.
Calculations based
on equations
a) Calculate the mass of carbon dioxide given off
when 1g of methanol is burned.
CH3OH
+ 2O2  CO2 + 2H2O
b) Calculate the mass of water produced when 3.2g
of ethanol is burned.
C2H5OH
+ 2O2  CO2 + 3H2O
c) Calculate the mass of oxygen required to burn
50g of methane.
CH4
+ 2O2  CO2 + 2H2O
d) Calculate the mass of water produced when 24g
of ethene is burned in oxygen
C2H4
+
3O2  2CO2 + 2H2O
Problem Solving
The combustion of alkanals releases heat energy.
PS
a)
Make a general statement linking the amount of heat
energy released and the number of carbon atoms in
the alkanal molecules.
b)
Predict the amount of heat energy
released, when 1 mole of pentanal
burns.
The octane numbers for some hydrocarbons are shown.
(i) Predict the octane number for hexane.
(ii) State a relationship between the
structure of the hydrocarbon and their
efficiency as fuels.
PS
a)
Complete the table
b)
Care had to be taken when using bromine solution.
Give a safety precaution, other than eye protection,
which should be taken when
completing this PPA.
Suggest a possible name for
hydrocarbon C.
c)
The diagram below shows how an alkane can be prepared
from an alkanoic acid.
The equation for the reaction is:
Alkanoic acid  alkane + carbon dioxide
Complete the table to show which alkanoic acid could
be used to produce butane.
Alkanoic acid
Alkane
ethanoic acid
propanoic acid
methane
ethane
butane
Hydroxy acids are compounds that contain both a
hydroxyl group and a carboxylic acid group within the
same molecule. These compounds are able to form
cyclic esters called lactones.
Draw the structural formula for the lactone formed
when this hydroxyl acid reacts.
• Lavender oil is produced from the
flowers by steam distillation. The
flowers are put into a flask with a
little water. Steam from a steam
generator is blown through them to
extract the oil. The mixture of
lavender oil and steam distils over.
It is condensed and collected.
• The pieces of apparatus which are
used to carry out this steam
distillation are shown.
• show the order in which the pieces of
apparatus should be arranged to
obtain the mixture.