9701_w14_qp_23.pdf

This document consists of 10 printed pages and 2 blank pages.

[Turn overIB14 11_9701_23/3RP UCLES 2014

*6698895364*

READ THESE INSTRUCTIONS FIRST

Write your Centre number, candidate number and name on all the work you hand in.Write in dark blue or black pen.You may use an HB pencil for any diagrams or graphs.Do not use staples, paper clips, glue or correction fl uid.DO NOT WRITE IN ANY BARCODES.

Answer all questions.Electronic calculators may be used.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.

At the end of the examination, fasten all your work securely together.The number of marks is given in brackets [ ] at the end of each question or part question.

CHEMISTRY 9701/23

Paper 2 Structured Questions AS Core October/November 2014

1 hour 15 minutes

Candidates answer on the Question Paper.

Additional Materials: Data Booklet

Cambridge International ExaminationsCambridge International Advanced Subsidiary and Advanced Level

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29701/23/O/N/14 UCLES 2014

Answer all the questions in the spaces provided.

1 (a) Successive ionisation energies for the elements fl uorine, F, to bromine, Br, are shown on the graph.

12 000

10 000

8000

6000

4000

2000

01 2 3

electrons removed4 5

ionisationenergy / kJ mol1

F

Cl

Br

(i) Explain why the fi rst ionisation energies decrease down the group.

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....................................................................................................................................... [3]

(ii) Explain why there is an increase in the successive ionisation energies of fl uorine.

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.............................................................................................................................................

....................................................................................................................................... [2]

Imranul IslamTypewriterGoing down the group the outer shell goes further from the nucleus, that causes for

Imranul IslamTypewriterreduced attraction between outer shell electrons and nucleus, and also the shielding

Imranul IslamTypewritereffect increases going down the group. So it gets easier to remove an electron going

Imranul IslamTypewriterdown the group, hence less energy is required.

Imranul IslamTypewriterAs every successive electron is removed, electron decreases although the nuclear

Imranul IslamTypewritercharge remains the same and also the shielding effect remains roughly constant.

Imranul IslamTypewriterSo, greater energy is required to overcome this attraction to bring out an electron.

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39701/23/O/N/14 UCLES 2014 [Turn over

(b) Group VII is the only group in the Periodic Table containing elements in all three states of matter at room conditions.

State and explain, in terms of intermolecular forces, the trend in the boiling points of the elements down Group VII.

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.............................................................................................................................................. [4]

(c) Compounds containing different halogen atoms covalently bonded together are called interhalogen compounds.

(i) One interhalogen compound can be prepared by the reaction between iodine and fl uorine. This compound has Mr = 222 and the percentage composition by mass: F, 42.8; I, 57.2.

Calculate the molecular formula of this interhalogen compound.

molecular formula ................................. [3]

(ii) Another interhalogen compound has the formula ICl.

Draw a dot-and-cross diagram of a molecule of this compound, showing outer shell electrons only. Explain whether or not you would expect this molecule to be polar.

.............................................................................................................................................

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....................................................................................................................................... [2]

Imranul IslamTypewriterAs all group 7 elements have simple molecular structure, their melting points and boiling

Imranul IslamTypewriterpoints are relatively low. Going down the group number of electrons per molecules increase

Imranul IslamTypewriterwhich also increase the chances of instantaneous dipole arising within molecules, thus


Imranul IslamTypewriteropportunities for more Van Der Waals forces between molecules being formed. So, as going

Imranul IslamTypewriterdown the group electrons increases, state of element also changes from solid to liquid to

Imranul IslamTypewritergas.

Imranul IslamTypewriterF

Imranul IslamTypewriterI

Imranul IslamTypewriter42.8 38


Imranul IslamTypewriter 57.2 254



Imranul IslamTypewriter1.12630.2252

Imranul IslamTypewriter0.22520.2252



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Imranul IslamTypewriterI Cl

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Imranul IslamTypewriterMolecule is polar as iodine and chlorine have different electronegativities.

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49701/23/O/N/14 UCLES 2014

(d) Some reactions involving chlorine and its compounds are shown in the reaction scheme below.

NaCl (aq) +W(aq)

Cl 2(g) Y(g)cold NaOH(aq)

hot NaOH(aq)

H2(g)

UV

NaCl (aq) +X(aq)

Z(s) Y(aq)AgNO3(aq)

bubbleinto water

(i) Give the formulae of W, X, Y and Z.

W ........................................................................................................................................

X .........................................................................................................................................

Y .........................................................................................................................................

Z .........................................................................................................................................[4]

(ii) Write an equation for the reaction of chlorine with hot NaOH(aq).

....................................................................................................................................... [2]

(iii) State the oxidation numbers of chlorine at the start and at the end of the reaction in (ii).

....................................................................................................................................... [2]

(iv) Write an ionic equation for the reaction of Y with AgNO3(aq). Include state symbols.

....................................................................................................................................... [1]

[Total: 23]


Imranul IslamTypewriterNaOCl


Imranul IslamTypewriterNaClO3

Imranul IslamTypewriterHCl


Imranul IslamTypewriterAgCl

Imranul IslamTypewriterNaOH + Cl2 -------------> NaCl + NaClO3 + H2O

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Imranul IslamTypewriter0 to -1 and +5

Imranul IslamTypewriterAg+ (aq) + Cl- (aq) ---------> AgCl (s)






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Question 2 starts on the next page.

69701/23/O/N/14 UCLES 2014

2 The Haber process for the manufacture of ammonia, NH3, was originally devised at the start of the 20th century and was developed into a full-scale industrial process by Carl Bosch in 1913.

The key step in the process is the reversible reaction of nitrogen and hydrogen in the presence of an iron catalyst.

N2(g) + 3H2(g) 2NH3(g) H = 92 kJ mol1

(a) The hydrogen for this reaction can be formed by reacting methane with steam, during which carbon monoxide is also produced. Write an equation for this reaction.

.............................................................................................................................................. [1]

(b) Use the Boltzmann distribution shown to explain why a catalyst increases the rate of this reaction.

number ofmolecules

kinetic energy

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.............................................................................................................................................. [4]

(c) Draw a three-dimensional diagram to show the shape of an ammonia molecule. Name this shape and state the bond angle.

shape ....................................................................................... bond angle ........................ [3]






Imranul IslamTypewriterCH4 (g) + H2O(g) --------------> 3H2 (g) + CO(g)


Imranul IslamTypewriter H N H


Imranul IslamTypewriterH









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Imranul IslamTypewriterPyramidal




Imranul IslamTypewriter107.5

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Imranul IslamTypewriterLet Ea1 be the activation energy without catalyst and Ea2 be the activation energy with catalyst.

Imranul IslamTypewriterThe graph above shows that when a catalyst is used the activation energy for the reaction

Imranul IslamTypewriterdecreases, this happens because the catalyst takes an alternative route for this reaction.



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(d) The Haber process is typically carried out at a temperature of 400 C. (i) With reference to Le Chateliers Principle and reaction kinetics, state and explain one

advantage and one disadvantage of using a higher temperature.

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(ii) State the expression for the equilibrium constant, Kp, for the formation of ammonia from nitrogen and hydrogen in the Haber process.

Kp =

[1]

(iii) 2.00 moles of nitrogen and 3.00 moles of hydrogen were put in a vessel and left to reach equilibrium.

At equilibrium, the pressure was 2.00 107 Pa and the mixture contained 1.60 moles of ammonia.

Calculate Kp. Include the units.

Kp = ............................

units = ............................[5]

[Total: 18]

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Imranul IslamTypewriterp[N2(g)] x p[H2(g)]

Imranul IslamTypewriterp[NH3(g)]





Imranul IslamTypewriterFor an exothermic reaction, when temperature is increased backward reaction increases at


Imranul IslamTypewriterequilibrium. This is a disadvantage as the forward reaction is the desired one for this process


Imranul IslamTypewriterand the advantage is that the rate of reaction is faster and equilibrium is also reached quickly.


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89701/23/O/N/14 UCLES 2014

3 P, Q, R and S are structural isomers with the molecular formula C5H10.

All four compounds readily decolourise bromine in the dark.

P, R and S do not exhibit stereoisomerism but Q exists as a pair of geometrical (cis-trans) isomers.

All four compounds react with hot concentrated, acidifi ed potassium manganate(VII) to produce a variety of products as shown in the table.

compound products

P CO2 and CH3CH2CH2CO2H

Q CH3CO2H and CH3CH2CO2H

R CO2 and T (C4H8O)

S CH3CO2H and (CH3)2CO

T reacts with 2,4-dinitrophenylhydrazine reagent, 2,4-DNPH, to form an orange crystalline product but does not react with Fehlings reagent.

(a) Give the structural formulae of P, Q, R, S and T.

P ..................................................................... Q ......................................................................

R ..................................................................... S ......................................................................

T ..................................................................... [5]

(b) (i) Explain what is meant by the term stereoisomerism.

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....................................................................................................................................... [2]

Imranul IslamTypewriterOrganic compounds having same molecular formula, but different arrangements of atoms or group of atoms.

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(ii) Draw the displayed formulae of the geometrical isomers of Q and name them both.

name ......................................................... name ........................................................ [2]

(c) Name the organic product of the reaction of T with sodium borohydride, NaBH4.

.............................................................................................................................................. [1]

[Total: 10]

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Imranul IslamTypewritercis-pent-2-ene


Imranul IslamTypewritertrans-pent-2-ene


Imranul IslamTypewriterCH3CH2CH(OH)CH3

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10

9701/23/O/N/14 UCLES 2014

4 A series of reactions based on propan-1-ol is shown.

CH3CH2CH2OH U (C3H8O)

VCH3CH2CO2H

reaction 2 HBr

steamcatalyst

reaction 1

reaction 3

CH3CH=CH2

(a) Suggest a suitable reagent and conditions for reaction 1.

.............................................................................................................................................. [2]

(b) (i) Write an equation for reaction 2, using [O] to represent the oxidising agent.

....................................................................................................................................... [1]

(ii) Suggest a suitable reagent and conditions for reaction 2.

....................................................................................................................................... [2]

(c) Give the structural formulae of U and V.

U ................................................................................................................................................

V ................................................................................................................................................[2]

(d) Suggest a suitable reagent and conditions for reaction 3.

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.............................................................................................................................................. [2]

[Total: 9]


Imranul IslamTypewriterAl2O3

Imranul IslamTypewriterCH3CH2CH2OH + 2 [ O ] --------> CH3CH2CO2H + H2O





Imranul IslamTypewriterAcidified potassium dichromate(VI)



Imranul IslamTypewriterCH3CH2(OH)CH2



Imranul IslamTypewriterCH3CH2BrCH2

Imranul IslamTypewriterNaOH in ethanol

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UCLES 2014

12

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