26 Jun For each of the following pairs of elements
Question
CHEMISTRY QUESTIONS
1. For each of the following pairs of elements, state whether the
compound formed is likely to be ionic or covalent. Give the formula
and name of the compound and give your reasons.
(a) K, S
(b) F, O
[2 x 4 marks]
2. Draw dot / cross (Lewis) diagrams for the compounds formed in
Question 1, showing only electrons in the outer orbit shell.
[2 2 marks]
3. For the following pairs of elements or compounds, state which would
have the higher melting point. In each case explain your answer.
(a) Na and O2
(b) MgCl2 and NaCl
(c) CO2 and SiO2
[3 x 3 marks]
4. Identify strongest intermolecular forces involved in each of the
following
(a) a sample of gaseous CO2;
(b) a mixture of water and methylamine (CH3NH2)
(c) a sample of liquid chloroform (CHCl3
In each case indicate how the intermolecular force(s) arise.
[9 marks]
5. Consider the following molecules.
IF5
C2H4
NH3
SbF5
AlCl3
H2O
CCl4
HCN
CO2
SF6
For each of the following properties, select one appropriate example
from the selection given above.
[1 5 marks]
(a)
A linear molecule
(b)
Two lone pairs on the central atom.
(c)
Tetrahedral in shape
(d)
Bond angles of approximately 107º.
(e)
Trigonal planar in shape
Note: Some molecules may have more than one of these properties
and some may not have any.
6. Name each of the following using the IUPAC system.
(a) CHF2CH(OH)CHBrCH3
CH3CHBrCF2C(CH3)2CHO
(b)
[2 2 marks]
(b) Draw either the full structural (display) formula or skeletal
structure for
the molecules in (a) and (b)
[2
marks]
8. Which of the following exist as a pair of optical isomers? Explain
your answer as fully as possible.
A.
CH3CH2CH2OH
C. CH3CH2CBr(OH)CH3
B.
CH3CH(OH)CH3
D. HOOCCH(OH)COOH
[2 marks]
9. Cinnamon is obtained from the bark of a tree. It is used in cooking to
provide a spicy scent and flavour to food. The spicy smell is caused
by the presence of an oil called cinnamaldehyde, a pale yellow
viscous liquid.
Cinnamaldehyde
(a) Cinnamaldehyde (C6H5CHCHCHO)
predominately the trans-isomer.
occurs
naturally
as
i) Draw the skeletal formula of the other geometric isomer of
C6H5CHCHCHO.
[2 marks]
(ii) Explain why C6H5CHCHCHO exhibits geometric isomerism.
[2 marks]
(b) Cinnamaldehyde reacts with liquid bromine.
i) Name the functional group present in cinnamaldehyde that
reacts with the bromine
.
[1 mark]
(ii) State the colour change you would see when bromine reacts
completely with cinnamaldehyde and give the structure of the
product formed in this reaction.
[2
marks]
(c) Cinnamaldehyde takes part in an addition reaction with
hydrogen bromide. Draw two possible structures for the
product of this reaction.
[2 marks]
(d)
Cinnamaldehyde can be made from cinnamyl alcohol by an
oxidation reaction.
Cinnamyl alcohol
Give the reagents and conditions
cinnamaldehyde from cinnamyl alcohol.
[3 marks]
for
the
formation
of
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