2011 h2 chemistry paper 1 suggested solutions

MINISTRY OF EDUCATION, SINGAPORE in collaboration with UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE General Certificate of Education Advanced Level Higher 2

CHEMISTRY 9647/01 Paper 1 Multiple Choice October/November 2011 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet

READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, Centre number and index number on the Answer Sheet in the spaces provided unless this has been done for you. There are forty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet.

This document consists of 17 printed pages and 1 blank page.

© UCLES & MOE 2011 [Turn over

Singapore Examinations and Assessment Board

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© UCLES & MOE 2011 9647/01/O/N/11

Section A

For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct.

1 Use of the Data Booklet is relevant to this question.

The sunlight-induced photolysis of water is being investigated as a useful source of the pollution-free fuel hydrogen.

2H2O � 2H2 + O2

It has been found that anatase, one of the three crystalline forms of the ionic compound TiO2, is a good catalyst for this reaction.

How many electrons are associated with each titanium ion in the anatase lattice?

A 18 B 19 C 20 D 22

2 Why is the first ionisation energy of neon higher than that of fluorine?

A Fluorine is more electronegative than neon.

B Neon has a complete octet, but fluorine does not.

C The atomic radius of fluorine is less than that of neon.

D The nuclear charge in neon is greater than that in fluorine.


Sodium percarbonate, (Na2CO3)x.y(H2O2), is an oxidising agent in some home and laundry cleaning products.

10.0 cm3 of 0.100 mol dm–3 sodium percarbonate releases 48.0 cm3 of carbon dioxide at room conditions on acidification.

An identical sample, on titration with 0.0500 mol dm–3 KMnO4, requires 24.0 cm3 before the first pink colour appears. KMnO4 reacts with H2O2 in the mole ratio 2 : 5.

What is the ratio y/x?

A 1/3 B 2/3 C 3/2 D 3/1

4 A given mass of ideal gas occupies a volume V and exerts a pressure p at 27°C.

At which temperature will the same mass of the ideal gas occupy the same volume V and exert a pressure 2p?

A 54°C B 54 K C 600°C D 600 K

Ti: 22 electronsTi4+: (22 - 4) electrons

neon has one more proton thanfluorine, i.e. greater nuclear charge;shielding effect remains constantacross the period;effective nuclear charge in neon isgreater;more energy is required to removethe valence electron from neon thanfrom fluorine

n(CO32-) = 0.00100x mol = n(CO2) = 0.00200 mol

x = 2

n(H2O2) = 0.00100y mol n(KMnO4) = 0.00120 mol0.00100y/0.00120 = 5/2y = 3

pV/T = constantpV/(273+27) = (2p)(V)/TT = 600 K

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© UCLES & MOE 2011 9647/01/O/N/11 [Turn over

5 The standard enthalpy change of combustion of but-1-ene, C4H8(g), is x kJ mol–1.

The standard enthalpy change of the reaction 2C2H4(g) � C4H8(g) is y kJ mol–1.

What is the standard enthalpy change of combustion of ethene, C2H4(g)?

A x/2 + y kJ mol–1

B x + y/2 kJ mol–1

C (x + y)/2 kJ mol–1

D (x – y)/2 kJ mol–1

6 The table shows the charge and radius of each of six ions.

ion J+ L+ M2+ X– Y– Z2–

radius / nm 0.14 0.18 0.15 0.14 0.18 0.15

The ionic solids JX, LY and MZ are of the same lattice type.

What is the correct order of their lattice energies, placing the most exothermic first?

A JX, MZ, LY B LY, MZ, JX C MZ, JX, LY D MZ, LY, JX

7 At temperatures below 13°C, shiny, ductile metallic tin, known as ‘white tin’, changes slowly into a grey powder which is brittle.

Data for each form of tin are given in the table.

ΔHfo / kJ mol–1 So / J K–1 mol–1

white grey

0

–2.09

51.4

44.1

What is the expression for ΔGf

o, in J mol–1, for the formation of grey tin from white tin at 12°C?

A ΔGfo = –2.09 – 285(–7.3)

B ΔGfo = –2.09 – 12(+7.3)

C ΔGfo = –2090 – 12(+7.3)

D ΔGfo = –2090 – 285(–7.3)

xC4H8(g) + 6O2(g) 4CO2(g) + 4H2O(l)

2C2H4(g) + 6O2(g)y + xy

standard enthalpy change of combustion: amount of energyreleased when 1 mole of ethene burns, i.e. (x + y)/2

lattice energy isproportional toproduct ofcharges, inverselyproportional tosum of ionic radii

standard entropy change = 44.1 - 51.4 = -7.3 J K-1 mol-1standard enthalpy change = -2090 J mol-1

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© UCLES & MOE 2011 9647/01/O/N/11

8 A student electrolyses concentrated aqueous sodium chloride using carbon electrodes. She

ensures that the solution is continually stirred.

What happens as the electrolysis proceeds?

A H2 is produced at the anode.

B HCl is formed.

C NaClO is formed.

D The NaCl gets more concentrated.


In many areas, tap water becomes slightly acidic due to dissolved carbon dioxide.

By considering the relevant Eo values, which metal will not be dissolved by tap water containing carbon dioxide?

A copper

B iron

C lead

D zinc

10 The diagram shows the apparatus needed to measure Eo for the reaction below.

Fe3+(aq) + e– Fe2+(aq)

What are the identities of X and Y?

X Y

A

B

C

D

Fe

Fe

Pt

Pt

Fe3+(aq)

Fe2+(aq) + Fe3+(aq)

Fe3+(aq)

Fe2+(aq) + Fe3+(aq)

hydrogen gas

platinum

hydrochloric acid

Y

X

chloride is oxidised to chlorine gas at theanode, water is reduced to H2 and OH- at the cathode, leaving NaOH in the solution;

chlorine disproportionates in cold NaOH toproduce NaClO

E(Cu2+/Cu) is the most positive, i.e. Cu has the leasttendency to be oxidised

5


11 Soft drinks often have sodium citrate added to them to act as a buffer.

Which statement about buffer solutions is correct?

A The pH of a buffer solution changes slightly when very large amounts of acid or base are added.

B The pH of a buffer solution increases very slightly when small amounts of acid are added.

C The pH of a buffer solution increases very slightly when small amounts of base are added.

D The pH of a buffer solution remains unchanged when small amounts of acid or base are added.

12 The reaction between NO2 and SO2 is a key stage in the formation of acid rain.

NO2(g) + SO2(g) � NO(g) + SO3(g)

The initial rate of this reaction was measured for different concentrations of reactants and the following results obtained.

[NO2] / mol dm–3 [SO2] / mol dm–3 relative rate

0.005

0.006

0.008

0.005

0.006

0.006

1.00

1.44

1.92

Which row gives the correct orders of reaction with respect to the two reactants?

order with respect to [NO2]

order with respect to [SO2]

A

B

C

D

1

1

2

2

0

1

0

1

×1.2

×1.33

×1.2 ×1.44

×1.33

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© UCLES & MOE 2011 9647/01/O/N/11

13 The rate of the decomposition of the diazonium cation,

C6H5N2+ + H2O � C6H5OH + H+ + N2

can be followed by measuring the time taken for the same volume of nitrogen to be produced from a range of diazonium cation concentrations.

To find the order of the reaction with respect to the diazonium cation, which would be the most suitable graph to plot using the data?

A [C6H5N2+] against time

B [C6H5N2+] against 1 / time

C volume N2 against time

D volume N2 against 1 / time

14 Which statement concerning only the elements in the third period, sodium to argon, is correct?

A The element that has exactly four atoms in its molecule is sulfur.

B The element with the highest electrical conductivity is aluminium.

C The element with the highest melting point is aluminium.

D The element with the largest anion is chlorine.

15 HCl is stable to heat, but HI decomposes into its elements when heated.

What is responsible for this difference?

A HI is a stronger reducing agent than HCl.

B HI is more volatile than HCl.

C The H-I bond is weaker than the H-Cl bond.

D The I-I bond is weaker than the Cl-Cl bond.


What volume of oxygen, measured under room conditions, can be obtained from the complete thermal decomposition of 8.2 g of calcium nitrate (Mr = 164)?

A 150 cm3 B 300 cm3 C 600 cm3 D 1200 cm3

plot of [C6H5N2+] against time is the most straightforward

method to determine order;if straight line with negative gradient obtained, zero order;if exponential curve with constant half-life obtained, first order;if curve with varying half-lives obtained, order is indeterminate,have to employ other methods to determine exact order

electrical conductivity isdirectly related to thenumber of delocalisedelectrons in the 'sea ofelectrons' in metallic lattice

thermal decomposition of HX involvesbreaking of H-X bonds;

less energy required to break H-Xbonds means easier to decompose

Ca(NO3)2 CaO + 2NO2 + 0.5O2

n(Ca(NO3)2) = 0.050 moln(O2) = 0.5 × 0.050 = 0.025 molV(O2) = 0.025 × 24 000 = 600 cm3

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17 In acid solution, dichromate(VI) ions oxidise hydrogen peroxide, H2O2. In alkaline solution,

hydrogen peroxide oxidises chromium(III) ions.

Which conditions of oxidation produce oxygen gas?

A both acid and alkaline oxidations

B neither acid nor alkaline oxidation

C only the acid oxidation

D only the alkaline oxidation

18 The enthalpy change of fusion of a solid is defined as the amount of energy, in J or kJ, required to melt one mole of a solid at its melting point.

The table shows the enthalpy changes of fusion of four successive elements, W to Z, in the third period (sodium to argon) of the Periodic Table.

element W X Y Z

enthalpy change of fusion / kJ mol–1 10.8 46.4 0.6 1.4

Which sequence of elements is represented by W to Z?

W X Y Z

A

B

C

D

Al

Na

P

Si

Si

Mg

S

P

P

Al

Cl

S

S

Si

Ar

Cl

19 Which statement about the molecule but-2-yn-1-ol is not correct?

OH

but-2-yn-1-ol

A The centre carbon atoms (2 and 3) are sp hybridised.

B The molecule decolourises warm acidified KMnO4.

C The terminal carbon atoms (1 and 4) are sp2 hybridised.

D The terminal carbon atoms (1 and 4) have tetrahedral geometry.

4 3 2 1

in order to produce oxygen gas,hydrogen peroxide must undergooxidation; this occurs only in acidsolution

enthalpy change of fusion is directlyrelated to melting point;

Si (giant covalent structure) has thehighest m.p., followed by Al (metallic lattice);

P and S (simple molecular structures)have low m.p.

terminal carbon atoms are sp3

hybridised

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© UCLES & MOE 2011 9647/01/O/N/11

20 The complete combustion of alkanes to produce carbon dioxide and water is an important

exothermic reaction.

Which line on the graph shows the relationship between the number of carbon atoms in the alkane and the number of moles of oxygen gas needed for complete combustion of the alkane?

21 Chloroethene, CH2=CHCl, is unreactive to nucleophiles whereas 3-chloropropene,

CH2=CHCH2Cl, is very reactive by comparison.

What explains the lack of reactivity of CH2=CHCl?

A Substituted alkenes undergo only electrophilic addition.

B The C=C double bond and the Cl atom are both electron withdrawing which stabilises CH2=CHCl.

C The electrons on the Cl atom delocalise into the � bond.

D The presence of the � bond prevents free rotation of the C-Cl bond thus decreasing the reactivity.

number of moles of oxygen gas

1 number of carbon atoms in alkane

D

C

B A

CxH2x+2 + (6x+2)/4 O2 xCO2 + (2x+2)/2 H2O

y = (6x+2)/4 = 1.5x + 0.5i.e. straight line with gradient 1.5, y-intercept 0.5

delocalisation of electrons from Cl into the pibond results in partial double bond character,hence rendering it much less reactive

9


22 Which species could be an intermediate in an SN1 substitution?

A CCH3

OH

O-

Cl

B CH2+

C

CN

H

+

D C+

CH3CH3

CH3

OH-

Br-

23 The diagram shows a reaction.

O

O

steam, H+

Z

What could be the final products Z?

A O

OH

+OH

B O

OH

+ OHOH

C O

OH

+ OHOH

OH

D OH+

O

OH

�– �–

SN1 mechanism proceeds with carbocation intermediate

hydration of alkene,followed by hydrolysis of ester

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© UCLES & MOE 2011 9647/01/O/N/11

24 A comparison is made of the rate of hydrolysis of four halogenocompounds by warm

NaOH(aq).

CH3CH2COCl C6H5Cl (CH3)3CBr (CH3)3CI W X Y Z

How will these rates compare?

fastest slowest

A

B

C

D

W

W

X

Z

Y

Z

Z

Y

Z

Y

Y

X

X

X

W

W

25 The reaction conditions for four different transformations are given below.

Which transformation has a set of conditions that is not correct?

A CH4(g) + Cl2(g) CH3Cl + HClUVlight

B C6H6(l) + HNO3(conc.) C6H5NO2 + H2Oconc. H2SO4

55°C

C

CH3

(l) + Cl2(aq) + HClAlCl3(s)

heat

CH3

Cl

D

OH OH

NO2

(aq) + HNO3(dilute) + H2O

acid chloride is the most susceptibleto hydrolysis due to its highly electrondeficient carbonyl carbon (which isbonded to two electronegative O andCl atoms); chlorobenzene is the least susceptibleto hydrolysis due to partial doublebond character of C-Cl;iodoalkane is more susceptible tohydrolysis than bromoalkane due toweaker H-I bond

conditions should be anhydrous foraluminium chloride to effectively actas Lewis acid catalyst

11


26 Compound P, C4H10O2, is an alcohol containing two –OH groups per molecule. It can be

oxidised in stages to compound Q, C4H8O2, and then to compound R, C4H6O2, which is a diketone.

Which pair of statements about the properties of P, Q and R is correct?

has 2 chiral centres reacts with alkaline aqueous iodine to give tri-iodomethane

A

B

C

D

P only

P only

P and Q only

P, Q and R

P, Q and R

Q and R only

Q and R only

P, Q and R

27 In the following two-step synthesis, Y a solid which is insoluble in water, is one of the components in the final reaction mixture.

O

OH

OH

PCl5, warmX

NH3

then heatY

What is Y?

A B C D

O

NH

O

NH2

OH

O

O-

NH3+

O

O-

NH2

NH4+

P: CH3C*H(OH)C*H(OH)CH3

Q: CH3COC*H(OH)CH3

R: CH3COCOCH3

chiral centres marked with *

all give positive result withiodoform test

X: carboxylic acid converted to acidchloride; 1° alcohol converted to 1°chloroalkaneY: acid chloride converted to amide;1° chloroalkane converted to 1°amine; 1° amine acts as anucleophile and reacts with amide

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© UCLES & MOE 2011 9647/01/O/N/11

28 Compounds X, Y and Z all react with sodium to release hydrogen but only one of them reacts

with 2,4-dinitrophenylhydrazine reagent.

Which combination could be X, Y and Z?

X Y Z

A

B

C

D

CH2OH

CH2OH

CH2OH

CH2OH

CH2OH

CHO

CH2OH

CO2H

CHO

CHO

CH2OH

CHO

CH2OH

CO2H

CHO

CO2H

CO2H

CO2H

CHO

CO2H

CHO

CO2H

CO2H

CO2H

29 The compounds responsible for the umami flavour of soy sauce are salts of glutamic acid.

HO2CCH2CH2CH(NH2)CO2H

glutamic acid

Glutamic acid has pKa values of 2.1, 4.1 and 9.5.

What is the structure of the major species in a solution of glutamic acid at pH 7?

A B

O2C-

CO2-

NH2

O2C-

CO2-

NH3+

C D

HO2C

CO2-

NH3+

HO2C

CO2H

NH3+

X: 1° alcohol and carboxylic acid react with sodiumY: carboxylic acid reacts with sodium; aldehyde reactswith 2,4-DNPHZ: carboxylic acid reacts with sodium

pKa(alpha-carboxylic acid) = 2.1 < 7pKa(R-carboxylic acid) = 4.1 < 7pKa(alpha-amine) = 9.5 > 7

13


30 Oseltamivir is an anti-viral drug.

OR

NH2 CO2CH2CH3

CONHCH3

[–OR is inert]

oseltamivir

What is the product when oseltamivir is heated with HCl(aq)?

A B

OR

NH3+

CO2CH2CH3

CONHCH3

OR

NH3+

CO2H

NH3+

C D

OR

NH3+

CO2CH2CH3

NH3+

OR

NH3+

CO2H

CONHCH3

acidic hydrolysis of amide and ester to formprotonated amine and carboxylic acid;

protonation of amine

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© UCLES & MOE 2011 9647/01/O/N/11

Section B

For each of the questions in this section, one or more of the three numbered statements 1 to 3 may be correct. Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against the statements that you consider to be correct). The responses A to D should be selected on the basis of

A B C D

1, 2 and 3 are

correct

1 and 2 only are correct


1 only is

correct

No other combination of statements is used as a correct response.

31 Which statements about relative molecular mass are correct?

1 It is the sum of the relative atomic masses of all the atoms within the molecule.

2 It is the ratio of the average mass of a molecule to the mass of a 12C atom.

3 It is the ratio of the mass of 1 mol of molecules to the mass of 1 mol of 1H atoms.

32 Which conditions are necessary when an electrode potential is measured using a standard hydrogen electrode as the reference electrode?

1 the use of hydrogen gas at 101 kPa (1 atm)

2 measurement of the e.m.f. when the current delivered by the cell is effectively zero

3 a pH of 1.0 for the solution at the hydrogen electrode

33 The three compounds X, Y and Z have the following structures.

NN

OH

OH N

NCO2CH3

CH=CH2 N

O X Y Z

Which statements about X, Y and Z are correct?

1 X and Z have the same empirical formula.

2 X and Y are isomers.

3 The Mr of Y is exactly twice that of Z.

2. should be 1/12 of mass of a 12Catom3. relative molecular mass iscompared with mass of a 12C atom

(D)

1. standard pressure = 1 atm2. when current flows, measured voltage acrossterminals is no longer e.m.f. but p.d.

3. [H+] = 0.10 mol dm-3, standardconc. should be 1 mol dm-3 (B)

C12H10O2N2 C12H10O2N2 C6H5ON

(A)

15


34 The kinetics of the zero order reaction P � Q were investigated under different conditions.

The table shows pairs of quantities that were plotted as graphs.

Which pairs gave the following graph?

y-axis x-axis

1

2

3

rate

rate constant

rate constant

time

time

temperature

35 What factors explain why a solution of aluminium chloride is acidic?

1 Chloride ions react with water to form hydrochloric acid.

2 Aluminium ions have a large charge / surface area ratio.

3 The H–O bonds are weaker in [Al(H2O)6]3+ than in H2O.

36 1-Bromopropane may be prepared by slowly adding concentrated sulfuric acid to a mixture of propan-1-ol and sodium bromide, and keeping the reaction mixture cool.

CH3CH2CH2OH + HBr � CH3CH2CH2Br + H2O

What would be a by-product of this reaction if the temperature is allowed to rise?

1 Br2

2 SO2

3 CH3CH(OH)CH3

y-axis

x-axis 0

0

1. chloride, being the conjugate base of a strong acid (weakconjugate base), does not react with water

aluminium chloride is acidicbecause aluminium ions, havinghigh charge density, hydrolyse inwater to produce hydrogen ions

(C)

zero order kinetics: rate is independent of [P]and hence does not vary with time

rate constant is dependent on temperature andpresence of catalyst, and hence does not varywith time

(B)

1. bromide is oxidised by conc. sulfuric acid to bromine2. conc. sulfuric acid is reduced by bromide to sulfur dioxide3. 1-bromopropane can undergo dehydration in the presence ofconc. sulfuric acid to produce propene, which then reacts withsteam (high temperature) to produce the Markovnikov'sproduct, propan-2-ol

(A)

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© UCLES & MOE 2011 9647/01/O/N/11

The responses A to D should be selected on the basis of

A B C D

1, 2 and 3 are

correct



1 only is

correct

No other combination of statements is used as a correct response.

37 Swine flu has caused great concern internationally. One widely used treatment is the anti-viral drug Tamilflu®.

O OCH2CH3

NH2

NH

O

CH3

Which statements about the Tamilflu® molecule are correct?

1 It contains an amide group.

2 It contains two ester groups.

3 It contains four chiral centres.

38 A catalytic converter is part of the exhaust system of many modern cars.

Which reactions occur in a catalytic converter?

1 2CO + 2NO � 2CO2 + N2

2 CO2 + NO � CO + NO2

3 2SO2 + 2NO � 2SO3 + N2

(CH3CH2)2CHO

ester

**

*

amide

(D)

catalytic converter converts toxic exhaust to harmless gases,hence should not produce CO, NO2 and SO3

(D)

17


39 Baeyer’s reagent is used to detect carbon-carbon double bonds: a dilute alkaline solution of

KMnO4 loses its pink colour in the presence of such a bond.

In which tests does a positive result involve a reduction in the oxidation number of the metal present in the reagent?

1 Baeyer’s test

2 Fehling’s test

3 Tollens’ test

40 Spider silk is a protein composed mainly of the three amino acids alanine, glycine and serine.

NH2CH(CH3)CO2H NH2CH2CO2H NH2CH(CH2OH)CO2H

alanine glycine serine

Which type of bonding can occur in the tertiary structure of spider silk?

1 van der Waals’ forces

2 hydrogen bonding

3 ionic bonding

1. Baeyer's reagent oxidises alkene to diol, it itself beingreduced from MnO4

- to MnO2

2/3. Both Fehling's solution and Tollens' reagent oxidisealdehyde to carboxylate, and are being reduced in the process (A)

van der Waals' forces between R-groups of alanine/glycine;hydrogen bonding between R-groups of serine

(B)

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© UCLES & MOE 2011 9647/01/O/N/11

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2011 h2 chemistry paper 1 suggested solutions

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