nss chemistry part 11 chemistry of carbon compounds
TRANSCRIPT
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7/23/2019 NSS Chemistry Part 11 Chemistry of Carbon Compounds
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H
P
N
1.
2.
a.
KAL Pas
rt 11 Ch
ming an
HKAL 199
Consider
#(i) G
(ii) D
ca
HKAL 199
Alcohol
(i) D
(ii)
t Paper
emistry
d Isomer
II Q5a
the followin
ive the hybr
raw allposs
rbon atoms
I Q4
has the stru
raw a three-
hat type of i
uestions
f Carbo
isms
compound
dization sta
ible three-d
a, b, c and d
cture CH3C
imensional
somerism c
:
Compo
F.
es of the car
mensional s
in one of th
(OH)C2H5.
representati
n be exhibit
1
nds
bon atoms a
tructures fo
structures.
n of E
ed by E?
, b, c and d.
F, indicati g the expected bond an
gles around
(5 ma
(2 ma
the
ks)
ks)
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b. (i) Draw the structure of threestructural isomers of E, all of which are alcohols.
#(ii) Describe how the reagent Zn/concentrated HCl can be used to distinguish E from the three structural
isomers.
(3 marks)
c. On treatment with dilute H2SO4(aq), E gives mainly two isomeric compounds, F and G, both of which have
the formula C4H8. On treatment with bromine, both F and G give a product H with formula C4H8Br2.(i) Draw structures for F, G and H.
(ii) What is the isomeric relationship between F and G?
(4 marks)
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3. HKAL 2008 II Q7a
Deduce the structure of isomeric compounds F and G, with formula 126HC , that have the following
characteristics:
Compound Characteristics
F It has a pair of enantiomers.
It loses its chiral centre after hydrogenation over Pt.
G It reacts with 2Br to give a single compound.
It reacts with HBr to give a single achiral compound.
(6 marks)
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4. HKAL 2009 II Q4a
The Table below lists the melting points and boiling points of cis-1,2-dichloroethene and
trans-1,2-dichloroethene:
(i) Explain why, in 1,2-dichloroethene, the carbon-carbon double bond cannot rotate freely.
(ii) Explain why
(I) cis-1,2-dichloroethene has a higher boiling point, and
(II) trans-1,2-dichloroethene has a higher melting point.
(6 marks)
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5. HKAL 2010 I Q4
Dimethyl fumarate can be found in most leather products since it is commonly used as a mould inhibitor.
However, it was banned in Europe for all kinds of consumer goods in March 2009 because it was found to
cause skin allergies. Compound A is an isomer of dimethyl fumarate. The structures and melting points of
these two compounds are given below:
(a) (i) Name the type of isomerism involved.
(ii) Explain why the melting point of Ais lower than that of dimethyl fumarate.
(3 marks)
(b) Both dimethyl fumarate and Acan be hydrolysed to their corresponding dicarboxylic acids, B and D.
(i) Explain why the melting point of Dis lower than that of B.
(ii) Explain why the
fH of Bis more negative than that of D.
(4 marks)
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6.
7.
HKAL 200
Consider
c. D
d.
HKAL 200
The three
(i) C
(ii)
I Q5a
the reaction:
raw the stru
ould the pr
II Q7b
-dimensiona
omment on t
ill P and Q
tures of all
duct rotate
l structures
he differenc
xhibit the s
possible ster
beam of pl
f two 2-chl
e, if any, in
me chemic
6
eoisomers o
ne polarize
robutanes (
hysical pro
l properties
the produc
light? Expl
andQ) are
erties betw
Explain yo
.
ain your ans
shown belo
en Pand Q
ur answer.
wer.
w:
.
(3 ma
ks)
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8. HKAL 1992 I Q1a
There are several isomers of benzenedicarboxylic acid.
(i) Draw the structures of all possible isomers of benzenedicarboxylic acid.
(ii) One of these isomers is used to make terylene. Outline the reaction involved.
(iii) On heating, one of the isomers gives a compound W, with formula C8H4O3. Give the structure of W.
(5 marks)
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9. HKAL 1992 II Q7
A carboxylic acid P, with a relative molecular mass less than 100, contains C, 55.8%; H,7.0%; and O, 37.2%
by mass. An attempt to convert P to its methyl ester Q by prolonged refluxing of P with methanol in the
presence of aqueous H2SO4gave the desired ester Q but with much of the starting material P unchanged.
a. Determine the molecular formula of P.
b. Give the structures of four carboxylic acids having the molecular formula you determined in (a). Give
the systematic names for any one of the carboxylic acids and its methyl ester.
c. Suggest, with explanations, two ways which would make the esterification go towards completion.
d. Which has a higher boiling point, the carboxylic acid or its methyl ester? Explain your answer.
e. Show, using equations, how you would convert Q to P.
(17 marks)
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10. HKAL 1994 II Q7a
What do you understand by the terms structural isomerism and stereoisomerism?
(3 marks)
11. HKAL 1994 II Q8c
Give a systemic name to each of the following compounds.
a.
b.
c.
(3 marks)
CH3CH CH
CH3
CH2
CH3
CH=CH2
CH3CH2CH2-O-C-CH2CH2CH3
O
CH3CH2-C-CHCH2CH3
O
OH
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13
. HKAL 19
The follo
(i) butene
(ii) 2-ami
In each c
. HKAL 19State the
6 II Q8b
ing compo
dioic acid, a
opropanoic
se, state the
9 II Q6celationship
nds can exi
d
acid.
type of iso
etween eac
st in isomeri
erism and d
pair of str
10
c forms:
raw suitable
ctures show
representati
n below:
ons for the i
somers.
(4 ma
(3 ma
ks)
ks)
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14. HKAL 2002 II Q7b
For each of the following pairs of molecules, identify their relationship as identical, enantiomeric, geometrical
isomeric or structural isomeric.
(5 marks)
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15. HKAL 2003 II Q6b
Compound A (C6H6O6) is an acyclic tribasic acid isolated from the leaves and tubers of Aconitum napellus.
Hydration of A gives two isomeric compounds, B and D. B is achiral, but D is chiral. Deduce the structures of
A, B and D.
(5 marks)
16. HKAL 2006 I Q6c
Answer the following multiple-choice question:
(i) Which of the following compounds has a pair of enantiomers??
Ans: B
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17. HKAL 2006 II Q5c
Deduce the structure of compound Don the basis of the information given below:
(1) Elemental analysis data show that Dhas the following composition by mass: C 40.0%, H 6.7%
and O 53.3%.
(2) The relative molecular mass of Dis estimated to be in the range of 172 to 182.
#(3) The infra-red spectrum of D shows, apart from the absorption of CH stretching near 2900 cm-1, a
strong and broad absorption around 3400 cm-1, and no appreciable absorption around 1700 cm-1.
(4) All carbon atoms of Dhave the same bonding environment.
(5) Dis highly soluble in water, and the solution does not decolorise bromine water.
(8 marks)
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18. HKAL 2006 II Q5b
Compound Bis a strong stimulant. Its structural formula is as follows:
(i) Give the systematic name of B.
(ii) In fact, the above structural formula can represent two stereoisomers.
(I) Draw three-dimensional structures of the two stereoisomers.
(II) State a physical property which is different for the two stereoisomers.
(iii) It is known that among the two stereoisomers, only B has stimulant activity while the other onedoes not. Why?
(iv) A person is suspected to have taken stimulant B. A urine sample of the person is sent for analysis.
Suggest a method to establish whether Bis present in the urine sample.
(7 marks)
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Alkanes and Alkenes
19. HKAL 1999 I Q5a
Under certain conditions, methane reacts with chlorine to give chloromethane as the major product.
(i) State the conditions for the reaction
(ii) Outline the mechanism and name the mechanistic steps of the reaction.
(iii) Is the reaction of methane with chlorine an appropriate method for the preparation of dichloromethane?
Explain.
(5 marks)
(i)
(ii)
(iii)
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20. HKAL 2001 I Q5a
Consider the reaction:
(D is deuterium, as isotope of hydrogen)
(i) Draw the structure of the major product.
(iii) Is the product optically active? Explain your answer.
(3 marks)
21. HKAL 2001 I Q6b
After some lessons in organic chemistry, a student remarked, Alkanes are more stable than alkenes, therefore
alkanes do not react with chlorine but alkenes do.
Do you agree with the student? Explain.
(3 marks)
(i)
(iii)
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22. HKAL 2004 II Q6b
Hydrocarbons G reacts with HBr to give J as the major product.
(i) Give the structure of J and its systematic name.
(iii) A student commented that J obtained from the above reaction is optically active. Do you agree with
the student? Explain.
(5 marks)
23. HKAL 2005 I Q6b (iii)
Which of the following statements concerning the hydrogenation of ethene is INCORRECT?
A. The hydrogenation is an exothermic process.
B. The hydrogenation occurs in the presence of a catalyst at room temperature.
C. The H-H bond is weak to allow the hydrogenation to occur.
D. Ethane is less energy rich than the starting materials.
Ans: C
(i)
(iii)
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24. HKAL 2007 I Q5a (ii)
Give the structure of the major organic product E in the following reaction. Indicate the stereochemistry of the
products as appropriate.
(1 mark)
25. HKAL 2007 II Q7b
Consider the following reaction:
(i) Give the structure of the major organic product L.
(1 mark)
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26. HKAL 2009 II Q4b
Neoprene, a synthetics rubber, can be obtained from buta-1,3-diene via the following route:
#(i) The reactant for Step 1is Br2. Propose a mechanism for the formation of Afrom buta-1,3-diene.
(ii) Suggest reactant(s) and conditions for each of Steps 2,3and 4.
#(iii) Explain why the strength of neoprene can be improved after heating it with sulphur.
(8 marks)
27. HKAL 1995 II Q9b
Identify the following unknown structure.
CH2=CHCO2CH3M CH3CH2CO2CH3
(1 mark)
M: Pd or Ni or Pt / H2
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28. HKAL 1991 II Q7a
State with explanations, what you would observe in each of the following experiments, and write equations for
the reactions.
(i) A mixture of pentane and bromine in tetrachloromethane is exposed to sunlight.
(ii) Propene is bubbled into aqueous alkaline potassium manganate(VII).
29. HKAL 1998 II Q5cGive the structures of the major organic products, G and H, in (i) and (ii) below.
#Outline a mechanism for the formation of the major product in each of the three reactions.
(i)
(ii)
(2 marks)
G: C
CH3
CH3
Br
CH2CH
3(i)
(ii) H: CH3CH2CH2OH
(i) The reddish brown bromine turns colourless (1)
The reaction is a free-radical substitution reaction (0.5)
Depending on the amount of bromine, various substitution products are obtained.
CH3CH2CH2CH2CH3+ Br2CH3CH2CH2CH2CH2Br or CH3CH2CH2CH2CHBr2etc (1)
(ii) The purple colour of KMnO4turns to colourless. (1)
KMnO4is reduced and the alkene is oxidized. (0.5)
CH3CH=CH2 C
OH
C
OH
CH3
H
H
H
KMnO4(1)
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Alkanols, Ketones/Aldehydes and Carboxylic acids
30. Show how you carry out the following conversions in the laboratory, giving the structures of intermediate
compounds and the reagents for each step.
a. HKAL 1995 II Q8b(ii)
CH3CH2CH2OH C
OH
CH3CH3
H (3 marks)
b. HKAL 1996 II Q9a(iv)
OH OH
OH
(3 marks)
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31. Outline chemical tests which would allow you to distinguish between the compounds in the following pairs.
Describe what you would observe in each case.
a. HKAL 1991 II Q9a (ii)
(2 marks)
b. HKAL 1991 II Q9a (iv)
C
H
CH2OHCH
3CH
2CH
2
CH3
CCH3CH
2CH
2
CH3
CH3
OH
(2 marks)
c. HKAL 1993 II Q8a(iv)
(3 marks)
Warm the compounds with acidified K2Cr2O7.
The primary alcohol will turn the solution from orange to green while the tertiary alcohol will not.
Warm the compounds with acidified K2Cr2O7.
The primary alcohol will turn the solution from orange to green while the tertiary alcohol will not.
Add solution of NaHCO3to the compound, C6H5COOH will react to give CO2while the phenol C6H5OH will not.
COOH
OH
OH
CH3
CH2OH
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d. HKAL 1995 II Q7a(iii)
(4 marks)
e. HKAL 1993 II Q8a(ii)
CH3CH2CH2CH2CHO CH3CH2COCH2CH3
(3 marks)
f. HKAL 1996 II Q7c
C
O
H
O
(2 marks)
Warm the compounds with acidified K2Cr2O7.
The aldehyde will turn the solution from orange to green while the ketone will not.
CH3
OH
CH2OH
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32. HKAL 1996 II Q7b
In an experiment, 25 g of (CH3)3COH react with 36 g of HCl to gives 28 g of (CH3)3CCl.
(i) Find the limiting reactant of the reaction,showing clearly your calculation.
(ii) Calculate the percentage yield of (CH3)CCl.
(3 marks)
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33. HKAL 2000 II Q7a
An acyclic compound, R(C7H12O) has a linear structure, R can be converted to S and then to T:
C7H12O C7H14O C7H16OLiAlH4 H2/Pd
R S T
Given that R exists as a mixture of geometrical isomers, S has a chiral carbon center, and T does not have any
chiral carbon center, deduce allpossible structures of R, S and T.
(8 marks)
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34. HKAL 2001 I Q8b
In an experiment to prepare propanal from propan-1-ol,
CH3CH2CH2OH CH3CH2CHOCr2O7
2-/ H+
heat
a side-product N (C6H12O2) was formed.
(i) What is N? Suggest how N is formed.
(ii) Suggest onemethod to separate propanal from a mixture of propanal and N.
(iii) Suggest twomethods to confirm the identity of propanal.
(3 marks)
(i)
(ii)
(iii)
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35. HKAL 2002 I Q5b
Suggest reagent(s) to accomplish each of the following single-step transformations:
(1 mark)
36. HKAL 2005 II Q6a
Formaldehyde (methanal) is one of the commonly found organic indoor air pollutants.
(i) Suggest a source of household formaldehyde.
#(ii) The indoor air quality (IAQ) standard for formaldehyde has been set at 0.10 ppm by volume.
Calculate the maximum allowable quantity of formaldehyde, in gram in a room of volume 200 m3at
298 K and 1.01 105N m
-2.
(You may assume that formaldehyde behaves as an ideal gas.)
(iii) Some indoor air purifiers remove formaldehyde by chemical means. Suggest one chemical for the
removal of formaldehyde with the formation of less harmful products.(iv) Name one other organic indoor air pollutant and suggest its source.
(7 marks)
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37. Identify the following unknown structure.
a. HKAL 1994 II Q7
CH3CH=CHCH2CH2COOHLiAlH4
(1 mark)
b. HKAL 1995 II Q9b(ii), (iv)
(ii)
CH3CH2CH2COOH CH3CH2CH2COClL
(1 mark)
(iv)
HOCH2CH2OH C
O
C
O
OCH2CH2On
N
(1 mark)
CH3CH=CHCH2CH2CH2OH
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38. HKAL 2002 II Q7d
Suggest a synthetic route, in not more than three steps, for the transformation of 3-methylbenzoic acid to
N,N-diethyl-3-methylbenzamide, a substance commonly used in mosquito repellant.
CO2H
CH3
CH3
CON(CH2CH
3)2
3-methylbenzoic acid N,N-diethyl-3-methylbenzamide
(2 marks)
39.Identify the following unknown structure.
a. HKAL 1993 II Q7a(iii)
(1 mark)
b. HKAL 1994 II Q7
(1 mark)
NH2CH3COCl
NH2CH3CH2COCl
N
O
N
H C
O
CH3
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. HKAL 19
The follo
which is
(i) N
(ii) G
(iii) S
7 II Q5b
ing equati
chiral comp
ame all func
ive one stru
ggest a met
n represents
und.
tional group
ture for E a
hod to separ
the acid hy
s in D.
d one for F.
ate E and F
30
rolysis of a
Draw a suit
rom the rea
dipeptide D
able represe
tion mixtur
to produce
ntation for t
.
compounds
e chiral pro
E and F, on
duct.
(5 ma
of
ks)
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41. HKAL 2007 I Q4a, b
(a) Consider the alkaline hydrolysis shown below:
Give the structure of product A.
(1 mark)
(b) Consider the acidic hydrolysis shown below:
(i) Give the structure of product B,
(ii) Suggest the amount of acid required for the hydrolysis of 1 mole of the ester. Explain
your answer.
(2 marks)
a.
b. (i)
(ii)
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(a)
(b
(c)
(d
(e)
(f)
. HKAL 20
3-Methyl
distinctiv
5.0 cm3o
L.
Suggest
Calculate
isoamyl a
Draw a la
What are
Outline t
cannot be
Suggest
9 I Q8
l-butyl etha
pleasant b
f isoamyl al
hat reagent
the mole ra
lcohol=0.81
belled diagr
the major co
e procedure
effectively
hy isoamyl
oate, com
nana odour
ohol is allo
Lmay be a
io of isoam
g cm-3; den
m of the as
mpounds pr
s to isolate i
eparated fr
alcohol is N
only known
and is used
wed to react
d give the r
yl alcohol t
ity of glacia
embly of ap
esent in the
soamyl acet
m the result
OT used in
32
as isoamyl
in food fla
with l5.0 c
action cond
glacial ace
l acetic acid
paratus use
esulting mi
te from the
ing mixture
xcess in thi
acetate, is a
ouring. In a
3of glacial
itions for thi
tic acid use
=1.05g cm-3
in this prep
ture at the e
resulting m
by fractiona
preparatio
naturally oc
n experime
acetic acid
s preparatio
in this pre
)
aration.
nd of this pr
xture. (It is
distillation.
.
curring com
t to prepare
in the prese
.
aration. (G
eparation?
known that
)
pound havi
the compo
ce of a rea
(l m
ven: densit
(2 m
(2 m
(l m
isoamyl ace
(3 ma
(l m
g a
nd,
ent
rk)
of
rk)
rk)
rk)
ate
ks)
rk)
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43. HKAL 1991 II Q9b
Suggest a possible structure for each of the compounds J, K and L below and explain briefly your deductions.
(i) J, C4H6O, on oxidation gives K, C4H6O2.
(2 marks)
(ii) L, C5H12O, can exist as a pair of enantiomers, and reacts with phosphorus pentachloride to give
hydrogen chloride.
(2 marks)
(i)
(ii)
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Important Organic Chemicals
44. HKAL 2002 II Q7c
A mixture of 2.8 g of butane-1,4-diol and 6.3 g of benzene-1,3-dicarbonyl chloride was heated at 215oC for 30
minutes to give 6.4 g of a polymer M.
HO(CH2)4OH
COCl
COCl
butane-1,4-diol benzene-1,3-dicarbonyl chloride
(i) Draw the repeating unit of M.
(ii) What type of polymerization is involved in the formation of M?
(iii) Calculate the percentage yield of M.
(5 marks)
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45. HKAL 1997 II Q6b
Saponification of 1 mol of fat G with NaOH(aq) produces 1 mol of a triol C3H8O3, 2 mol of
CH3(CH2)16CO2-Na
+and 1 mol of CH3(CH2)14CO2
-Na
+.
(i) If G is optically active, suggest its structure. Explain.
(ii) If G is optically inactive, suggest its structure.
(iii) What is the minimumnumber of moles of base required for the complete saponification of 1 mol of G?
(4 marks)
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(i)
(ii
(ii
. HKAL 19
Dacron is
shown be
Suggest t
Draw the
involved.
) How can
9 II Q5c
the most co
ow.
o types of
structures
Dacron be d
mon of th
aterial whi
f the two
egraded in t
group of p
ch can be m
onomers us
e environm
37
lymers kno
de from po
ed in manu
nt?
n as polyes
yesters.
acturing Da
ters. A seg
cron. Name
ent of the p
the type of
lymer chai
polymerizat
(5 ma
is
ion
ks)
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47. HKAL 1999 II Q6b
(i) Draw the structure, showing two repeating units, for each of the following polymeric materials:
(I) poly(chloroethene) and
(II) cellulose
(ii) Large quantities of poly(chloroethene) and cellulose used in daily life, Suggest, with explanation, an
appropriate waste disposal method for each material.
(5 marks)
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a.
b.
. HKAL 20
Sodium s
sodium h
(i) D
(ii)
(iii) E
ProductJ, fr
(i) D
(ii) St
(iii) St
0 II Q6
tearate CH3
droxide sol
raw the stru
ith the help
plain why
om the trans
raw the stru
ate oneadv
ate oneenvi
CH2)16CO2-
tion.
ture of the t
of equation(
ashing sod
formation b
ture ofJ.
ntage of usi
ronmental p
Na+, the m
riglyceride.
s), describe
, Na2CO3
elow, is co
ngJas a det
oblem asso
39
st common
he chemistr
10H2O, can
monly-used
ergent.
iated with t
soap, can
y when soap
help to redu
household d
e use ofJ.
e made by
is added to
ce the hardn
etergent.
heating a tr
hard water.
ess the wate
iglyceride
.
(4 ma
(3 ma
ith
ks)
ks)
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c. Dodecyl
(i) E
(ii) S
lucoside is
plain why
ggest how
new deterg
edocyl gluc
odecyl gluc
ent.
oside can be
oside can be
40
used in the
degraded i
cleansing of
the environ
oily dirts.
ment.
(4 ma ks)
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. HKAL 20
Aspartam
(i)
C
as
(ii)
(iii)
In
S
5 II Q5b
e is a comm
opy the stru
terisk.
ith referenc
a coffee sh
ggest a reas
nly used ar
cture of asp
to its struc
op, a packet
on for inclu
ificial swee
artame into
ure, explain
of sweeten
ing silicon
41
ener.
your answe
why asparta
er contains
ioxide in th
book, and
me is unsta
bout 5% of
e packet.
mark each
le in cookin
aspartame
chiral carbo
g.
nd 95% of
atom with
silicon diox
(4 ma
an
de.
ks)
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50. HKAL 2006 II Q7a
In the past, people chewed willow bark to ease their pain and to lower fever. Later on, chemists identified
salicin as the active ingredient in willow bark.
salicin
Salicin undergoes acid hydrolysis to give glucose and 2-hydroxybenzyl alcohol.
#(i) Suggest a chemical test to distinguish between salicin and glucose. Account for the difference in
results of your suggested test.
(ii) 2-Hydroxybenzyl alcohol can be converted in two steps to acetylsalicylic acid, which is the active
ingredient of aspirin.
2-hydroxybenzyl alcohol acetylsalicylic acid
(I) Give the reagents used in Step 1and in Step 2.
(II) In a typical experiment, 2.0 g of 2-hydroxybenzyl alcohol gives 2.0 g of acetylsalicylic acid.
Calculate the percentage yield of the conversion.
(7 marks)
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(i)
(ii
. HKAL 2
Polyethe
diagram
Give the
Polyethe
(I) D
(II)
007 II Q6d
e terephthal
elow shows
eagent(s) an
e naphthalat
raw the stru
hich polym
te (PET) is
a route for t
d condition
e (PEN) is a
ture of a re
r, PET or P
a polymer
he synthesis
for each of
polymer fo
eating unit
N, do you
43
sed in maki
of PET.
Steps 1, 2, 3
med from n
f PEN.
xpect to be
ng clothing
and 4.
phthalic aci
more rigid?
ibres and s
d and ethan
Explain.
ft drink bot
-1,2-diol.
les. The f
(6 ma
ow
ks)
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52. HKAL 2010 II Q4d
Polyethylene terephthalate (PET) is a polymer commonly used in making soft drink bottles.
(i) Suggest a synthetic route with no more than three stepsto convert benzene-1,4-dicarbaldehyde
to PET. (You are NOT allowed to use organic reagents with more than three carbon atoms.)
(ii) Suggest why PET as compared with polystyrene, is more readily degraded in the environment.
(4 marks)
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iscellane
. HKAL 20
Identify
ous
0 II Q6e
, M and N i the followi
ng reactions
45
:
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54. HKAL 2002 II Q5c
Consider the substances listed below:
butane benzoic acid dichlorodifluoromethane
ethanoic acid hexane polystyrene
propanone tetrachloromethane triethylamine
For each of the descriptions of physical properties from (a) to (h) below, choose from the above list, one
substance which best fits the description.
(i) a colourless, flammable gas
(ii) a colourless liquid with a sour odour
(iii) a colourless, water miscible, flammable liquid
(iv) a colourless, non-flammable liquid
(v) a colourless liquid with a fishy smell
(vi) a colourless, water immiscible, flammable liquid
(vii) a white solid which is insoluble in both cold and hot water
(viii) a white solid which is insoluble in cold water, but soluble in hot water
(8 marks)
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55. HKAL 2003 I Q6b
The weakest chemical bond in an organic compound always breaks first in a chemical reaction.
The above statement is not always true. Give one example for which the statement is true and one example for
which the statement is not true. Explain each case briefly.
(4 marks)