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CHEM1101
2014-J-3
June 2014
All terpenes are derived from isoprene and many, such as myrcene, (R)-citronellal and
geraniol, are used in the perfume industry.
Explain the differences in boiling points of these four compounds in terms of the type
and size of the intermolecular forces present.
CHEM1101
2014-N-6
November 2014
• Complete the table concerning two of the isomers of C3H6O2. Identify the geometry
around each atom marked with an asterisk and the list the major intermolecular forces
present in the liquid.
Isomer
A
B
Chemical
structure
Geometry
Major
intermolecular
forces in liquid
The boiling point of isomer A is 141 °C and that of isomer B is 60 °C. Explain why
the boiling point of A is higher than B?
5
CHEM1101
2013-J-3
June 2013
• Intermolecular forces are responsible for the physical properties of many compounds.
What are dispersion forces?
The boiling points of F2, Cl2 and Br2 are 85, 239 and 338 K, respectively. Where
would you expect the boiling point of I2? Give reasons.
Marks
3
CHEM1101
2013-N-8
November 2013
• In terms of the type and size of intermolecular forces involved, explain the trend in
boiling points of the following compounds.
Substance
Stick structure
Boiling Point (°C)
ethane, C2H6
−89
2-methylpropane, C4H10
−12
butane, C4H10
−1
water, H2O
100
THE REMAINDER OF THIS PAGE IS FOR ROUGH WORKING ONLY.
Marks
4
CHEM1101
2012-J-15
June 2012
Boiling
Boiling
pointPoint
(deg.(°C)
Celcius)
• The figure below shows the boiling points of Group 14 and Group 17 hydrides as a
function of the period (row) of the periodic table.
0
HF
-50
HI
-100
-150
HBr
HCl
CH4
SiH4
2
3
GeH4
4
SnH4
5
Period
Period
It is apparent from this figure that:
- the tetrahydrides have lower boiling points than the monohydrides,
- the boiling points increase with period, with the exception of HF.
Explain these features.
Marks
4
CHEM1101
2012-J-15
June 2012
CHEM1101
2012-N-7
November 2012
i) N2O is sparingly soluble in water. What does this tell you about the strength of any
hydrogen bonding that exists? Rationalise your answer in terms of the structures of
the H2O and N2O molecules.
THE REMAINDER OF THIS PAGE IS FOR ROUGH WORKING ONLY.
Marks
2
CHEM1101
2010-J-14
June 2010
• Rationalise the order of the boiling points of the following liquids in terms of their
intermolecular forces.
liquid
F2
HCl
HBr
HI
Cl2
HF
Br2
I2
b.p. (° C)
–188
–85
–67
–35
–34
20
59
184
Marks
4
CHEM1101
2009-J-14
22/05(a)
• Explain the trend in the following table in terms of the type and size of intermolecular
forces.
Substance
Boiling point (oC)
CH3CH3
–89
CH3CH2CH2CH3
–1
CH3CH2–O–CH2CH3
35
CH3CH2OH
78
H2O
100
There are two isomers with the molecular formula C4H10.
CH3–CH2–CH2–CH3
butane
CH3
C H
H 3C
CH3
2-methylpropane
Discuss which isomer will have the greater intermolecular forces.
Marks
6
CHEM1101
2006-J-10
June 2006
• List the following five solids in order of increasing melting points.
NaCl, H2, CH4, H2O, SiO2
Briefly explain your ordering based on the types of forces that are involved.
List those that are electrical conductors when molten. Briefly explain your answers.
Marks
4
CHEM1101
2006-N-7
November 2006
• List the following five solids in order of increasing melting points.
NaCl, H2, CH4, H2O, SiO2
Briefly explain your ordering based on the types of forces that are involved.
List those that are electrical conductors when molten. Briefly explain your answers.
Marks
4