Answer ALL questions.
MODULE 1: FUNDAMENTALS OF CHEMISTRY
1.
(a)
In 1808, John Dalton proposed his atomic theory. However, much of our current knowledge
has disproven aspects of the theory.
(i) Outline FOUR postulates of this theory.
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(ii)
Identify and explain which TWO of these postulates have been majorly disproven due
to modern knowledge.
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(iii) Refer to THREE criteria considered when a theory is accepted, and relate ONE of
these to Dalton’s theory.
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(b)
The modern atom is known to comprise several species of subatomic particles.
(i)
Name and compare the THREE main subatomic particles within a neutral atom based
on their relative charges, masses, location and behavior in magnetic fields.
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(ii)
Define the term ‘isotope,’ making reference to EACH of the subatomic particles
mentioned above and variation in chemical and physical properties.
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(iii) A radioisotope of carbon, 146𝐶 , has a neutron to proton ratio higher than stable. Write
one possible nuclear equation of its decay to form a nuclide of lower neutron to
proton ratio.
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(c)
A sample of hydrogen gas is excited electrically and the resulting radiation passed through a
prism, detected and analyzed. The result is a spectrum produced on a computer.
(i)
What is the name given to the spectrum produced? Give TWO characteristics of this
spectrum as well.
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(ii)
The analysis produced light in the visible spectrum. State the name given to this
series and describe the nature of the electron transitions occurring.
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(iii) Explain how the production of this spectrum gives evidence for the existence of
energy levels in the atom, making specific reference to at least ONE assumption of
the Bohr model.
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(d)
As period 3 of the periodic table is crossed from left to right, there is a general increase in
first ionization energy, however an anomalous change occurs between the alkaline earth
metal and the triel element, and again between the pnictogen and chalcogen of the period.
(i)
Define what is meant by ‘first ionization energy,’ and explain the general increase in
first ionization energy across the period.
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(ii)
Explain the anomalous changes mentioned above.
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(iii) One of the anomalous changes referred to above can be explained based on the
differences between TWO types of orbitals. Draw these orbitals, and state the name
of the property that varies between them that results in the aforementioned anomalies.
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(iv) The information above speaks to first ionization energies across DIFFERENT
elements. Explain how SUCCESSIVE ionization energies of the same element
provide evidence for shells in an atom. Using the axes provided, also show how ALL
successive ionization energies vary for the sodium atom.
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2.
(a)
Various forces of attraction exist between particles, and account for many properties of
compounds. Account, or suggest an explanation, for EACH of the following observations
(you have NO choice):
(i)
At very low temperatures (-248.6°C), Neon can solidify.
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(ii)
Water has the highest boiling point of the binary hydrides.
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(iii) n-pentane has a higher boiling point than 2,2-dimethylpropane.
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(iv) The density of ice is lower than the liquid state of water.
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(v)
The experimentally determined relative molecular mass of ethanoic acid (CH3COOH)
was found to be 120.
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(vi) The boiling point of cis-1,2-dichloroethane is greater than that of trans-1,2dichloroethane. (Refer to the structures below):
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(vii) Water can dissolve many polar and charged substances.
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(viii) Boiling point of the halogens increases down the group.
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(b)
BF3 and NH3 react in a Lewis acid-base reaction to form the addition compound BF3NH3.
Draw the structures of the THREE species mentioned, and name the bond formed between
them.
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(c)
VSEPR Theory allows a prediction of the molecular geometry of compounds.
(i)
Give THREE principles upon which VSEPR Theory is based.
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(ii)
Describe and compare the electron and molecular geometries of methane (CH4) and
ammonia (NH3).
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(iii) Explain the term ‘hybridization’ and relate it to the planarity of the ethene molecule.
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(iv) Define the terms ‘resonance’ and ‘𝜋 bonds’ and relate them to the structure of
benzene.
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(d)
Reactions can be described as either endothermic or exothermic.
(i)
Differentiate between endothermic and exothermic reactions, using suitable energy
profile diagrams and making reference to bond formation and bond dissociation.
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(ii)
Account for the following statements:
The enthalpy of formation of Al2O3 cannot be easily experimentally determined.
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The enthalpy of formation of CO (carbon monoxide) cannot be experimentally
determined.
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(iii) Name and state the law that allows one to determine the enthalpy of formation of CO
indirectly.
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(iv) Draw an energy cycle diagram to show how knowledge of the heats of combustion of
Carbon and Carbon monoxide could permit determination of the enthalpy of
formation using the law named above.
(e)
The lattice energy of an ionic compound is very difficult to determine experimentally.
(i)
Define ‘lattice energy.’
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(ii)
Draw a Born-Haber Cycle for the formation of AlCl3.
(iii) It was determined that the lattice energy of AlCl3 is significantly different from its
experimental lattice energy. Explain what this suggests about its bonding.
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(iv) Give TWO main factors that affect lattice energy.
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MODULE 2: KINETICS AND EQUILIBRIA
3.
(a)
The following results were obtained for the hydrolysis of 2-bromo-2-methylpropane (CH3—
C(CH3)Br—CH3), by aqueous sodium hydroxide at 298K. The equation is:
CH3—C(CH3)Br—CH3 + OH- → CH3—C(CH3)(OH)—CH3 + BrConcentration of 2-bromo-
Concentration of OH-
Initial rate of hydrolysis/
2-methylpropane/mol dm-3
ions/ mol dm-3
mol dm-3 s-1
0.100
0.500
0.0020
0.100
0.250
0.0020
0.075
0.250
0.0015
0.050
0.250
0.0010
0.025
0.250
0.0005
(i)
Determine the order of the reaction with respect to:
(a) 2-bromo-2-methylpropane
(b) Hydroxide ions
(ii)
Write the rate expression for the reaction, and give the units of the rate constant.
(v)
Suggest ONE method by which the rate of this reaction could be determined in the
laboratory, including at least TWO materials necessary.
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(vi) Apart from the one mentioned above, give FOUR other possible methods of
determining the rate of a reaction.
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(b)
The following are two statements relevant to the issue of obtaining maximum yields in
industrial processes as quickly as possible.
‘The equilibrium yields of exothermic reactions increase with decreasing temperatures.’
‘The rates of all chemical reactions increase with increasing temperatures.’
(i)
State Le Chatelier’s Principle.
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(ii)
Explain why both of these statements are correct.
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(iii) Using a specific example, state how industrialists deal with the conflict between these
statements.
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(iv) With reference to collision theory and drawing suitable graphs, explain the effect of
temperature AND catalysts on rate of a reaction.
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(v)
Outline a suitable method to determine the equilibrium constant of the acid-catalyzed
esterification reaction between ethanoic acid and ethanol.
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MODULE 3: CHEMISTRY OF THE ELEMENTS
4.
(a)
Group VII is unique in the periodic table as it is the only group that has elements in all three states
of matter at standard conditions.
(i) Explain the trend in density down the group.
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(ii)
Iodine produces different products when it reacts with thiosulphate (S2O32-) than the
halogens above it. Using TWO relevant equations, describe these reactions AND describe
the trend down the group that accounts for this difference.
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(iii) Fluorine gas cannot be used to displace other halide ions from solution. Give the reason for
this and write ONE relevant equation.
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(iv) Write the ionic equation of fluorine gas with an alkali.
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(v)
The other halogens react differently with potassium hydroxide, for example. Write THREE
relevant reactions and the temperatures at which they occur to show the reactions of ONE
halogen with potassium hydroxide solution.
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(vi) Describe the reactions of the halogens with hydrogen gas.
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(vii) State the trend in bond energy of the halogens in their homoatomic molecules (elemental
states), and suggest ONE reason why fluorine has a LOWER bond energy than chlorine.
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(viii) The trend in the strengths of the hydrohalic acids is directly related to the trend in their
thermal stabilities. Explain these trends, making reference to bond energies.
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(ix) The reactions of the halide ions beneath chlorine with sulfuric acid result in the evolution
of the halogen gases in addition to steamy fumes that form white fumes with ammonia gas.
Explain why ONLY this fume product is produced with chlorine and write THREE
equations to illustrate the difference between these reactions.
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(x)
On reaction with concentrated sulphuric acid, hydrogen iodide produces iodine gas and one
of THREE sulphur-containing compounds. Name EACH of them, and write their chemical
formulae.
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(b)
Transition elements exhibit very unique properties, such as the formation of coloured compounds.
(i)
Define ‘transition element.’
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(ii)
Give FOUR characteristics of transition elements, not including coloured compound
formation.
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(iii) State and account for the differences between transition metals and calcium, a typical sblock element, with respect to EACH of the following properties:
Melting point
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Density
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Atomic Radius
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First Ionization Energy
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Conductivity
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(iv) The ionization energies and atomic radii of the transition metals vary across the d-block.
Explain why this variation is relatively small.
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(v)
The transition elements in their neutral states do not all have filled 4s orbitals. Identify
these elements and explain why this is so.
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(vi) In the space provided below, write the names and common oxidation states of FIVE
transition elements.
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(vii) Below is a series of reactions involving transition metals. In the blank boxes, write the
chemical formulae of the species involved, then write their colours on the blank lines.
(viii) State and explain the principle operating in the Cobalt, Copper and Chromium reactions
above.
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(ix) With reference to the above principle, explain the relationship between carbon monoxide,
haemoglobin, and hypoxemia. Include mention of stability constants and a possible
treatment for the above condition.
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(x)
State whether Fe2+ ions are good reducing or oxidizing agents, and, with writing its FULL
electronic configuration in s, p, d, f notation, explain why this is so.
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(xi) The scandium and zinc ions generate solutions of the same appearance, while each of the
other transition metal ions exhibit solutions of varying colours. Explain, with reference to
the colours of THREE aqueous transition metal ion colours, why these varying colours are
observed and why scandium and zinc are different.
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(xii) Compare the electronic configurations of Cu+ and Mn2+. Using the box notation for their
valence shells, explain the paramagnetic and diamagnetic properties of either ion.
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(xiii) Suggest ONE reason for the catalytic properties of transition metals, and give THREE
specific examples of reactions catalysed by transition metals.
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5.
(a)
A series of qualitative tests were carried out on a mixture, Z, of 2 soluble salts and one insoluble
salt. The incomplete results are given in the table below.
TABLE 1: QUALITATIVE TESTS CARRIED OUT ON A MIXTURE OF TWO
SOLUBLE SALTS AND ONE INSOLUBLE SALT
Qualitative Test
Observation
Inference
Z was mixed with adequate
distilled water and stirred.
This mixture was filtered and
the filtrate, A, divided into 5
equal volume portions. The
residue, B, was washed and
dried.

 Ba2+ present.
To one portion of A, sodium
 White precipitate formed
 Al3+, Pb2+, or Zn2+ ions
hydroxide was added until in

A platinum wire was cleaned,
dipped in dilute HCl, then
dipped into B. This wire was
then placed into the flame of a
Bunsen burner.
present.

excess. The resulting solution
was warmed, and any gas
 Colourless, pungent gas
evolved tested with moist red
evolved which turns moist
litmus paper.
red litmus blue.

reaction required
To another portion of A,
 White precipitate formed
aqueous ammonia was added

 Al3+ or Pb2+ ions present.
until in excess.

 No precipitate formed.
 Al3+ ions present.
Another portion of A was
 No gas was evolved.
mixed with concentrated
 Solution turned orange in
sulfuric acid.
colour.



reaction required
This portion was added to a

 NO3- present.

separating funnel, and a
solution of FeSO4 was added
reaction required
to form a layer on top of the
portion of A.
To another portion of A,
 Colourless, pungent gas
granulated zinc and aqueous
evolved which turns moist
sodium hydroxide were
red litmus blue.


added, and the mixture

heated.
reaction required
The final portion of A was
 Red-brown precipitate
mixed with aqueous silver

formed.
nitrate.
(i)
Complete the table above to indicate any missing tests, observations, or inferences- writing
equations where necessary.
(ii)
Suggest the identities of the THREE salts in the mixture Z.
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(iii) The first test involves a Bunsen burner. Explain the principle upon which this test is based.
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(iv) A student has accidentally mislabelled three bottles containing soluble salt solutionssodium sulphate, sulphite and carbonate. Outline a method allowing him to differentiate
between the three solutions.
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END OF TEST
IF YOU FINISH BEFORE TIME IS CALLED, CHECK YOUR WORK ON THIS TEST.