jan 2007 unit 1 - MS

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General Marking Guidance

All candidates must receive the same treatment. Examiners must mark thefirst candidate in exactly the same way as they mark the last.

Mark schemes should be applied positively. Candidates must be rewarded forwhat they have shown they can do rather than penalised for omissions.

Examiners should mark according to the mark scheme not according to theirperception of where the grade boundaries may lie.

There is no ceiling on achievement. All marks on the mark scheme should beused appropriately.

All the marks on the mark scheme are designed to be awarded. Examinersshould always award full marks if deserved, i.e. if the answer matches the

mark scheme. Examiners should also be prepared to award zero marks if thecandidates response is not worthy of credit according to the mark scheme.

Where some judgement is required, mark schemes will provide the principlesby which marks will be awarded and exemplification may be limited.

When examiners are in doubt regarding the application of the mark schemeto a candidates response, the team leader must be consulted.

Crossed out work should be marked UNLESS the candidate has replaced itwith an alternative response.

Using the mark scheme

1 / means that the responses are alternatives and either answer should receive full credit.2 ( ) means that a phrase/word is not essential for the award of the mark, but helps the examiner to get the sense of

the expected answer.3 [ ] words inside square brackets are instructions or guidance for examiners.4 Phrases/words in bold indicate that the meaning of the phrase or the actual word is essential to the answer.5 ecf/TE/cq (error carried forward) means that a wrong answer given in an earlier part of a question is used correctly in

answer to a later part of the same question.

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QuestionNumber

Correct Answer Acceptable Answers Reject Mark

1.(d)(i)

Empirical formula Cu2CO5H2(1) for dividing by atomic mass(1) stating empirical formula

Cu C O H

57.563.5

5.4012

36.216

0.9001

0.906 0.450 2.26 0.9002.01 1 5.02 2.00

Correct answer withoutworking scores (2)

Use of atomicnumber scores 0

2

QuestionNumber


1.(d)(ii) Empirical formula mass = 221 = MrMolecular formula Cu2CO5H2

Must show use of 221

If use atomic number in(i)allow mark for Cu2CO5H and220

Allow any formula thatadds up to the correctmolecular formula

1

QuestionNumber


1.(e) (Highest = 65Cu + 2 37Cl) = 139 (1)(Lowest = 63Cu + 2 35Cl) = 133 (1)Ignore units 2

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Qu stioneNumber


2.(a Lithiumcarmine/ red/ magenta/ crimson

y ombination of these or prefacedby p or rk

Potassium

S

l

scarlet

e or purple

a e or yellow-a e

Brick-red)

An cdee da

: clila

odium: yellow

three correct 2 marksAlTwo correct 1 mark

mauvor ngor ng

2

Qu stioneNumber


2.(b Electrons (absorb heat energy and) arepromoted (to higher level) (1)

elight/radiation (of characteristiccolour) (1)

Excitedrase that implies

leve

o e references to

If answer based onabsorption spectrascores zero

Colour or energy

2

)

Th y drop back and emit

any phmovement to higher

l

ign rshells, sub-shells, etc.

QuestionNumber


2.(c)(i) LiCl+ H2SO

Ignore state symbols

Mu ip

2LiCl+H2SO4Li2SO4+2HCl

1

4 LiHSO4 + HCl lt les

QuestionNumber


2.(c)(ii) K2CO3 + 2HNO3 2KNO3 + H2O+ CO2

CO32- + 2H+ H2O + CO2 /H2CO3

CO32- + H+ HCO3

-

Ignore state symbols and spectatorions

Multiples

K2CO3 + 2HNO32KNO3 + H2CO3

K2CO3 +HNO3KNO3 +KHCO3

1

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Qu stioneNumber


2.(c)(iii) NaI + AgNO3 AgI + NaNO3

o symbols and spectator

Multiples

+ + I AgI

1

Ign re state

ions

Ag

QuestionNumber


2.(d)(i) uld be (very)a l (1)

r

ORDifference in electronegativity small/similar (1)Therefore share (pair of) electrons /no

If both routes given. Mark both out of2 and then score higher hark.

a

nDistort for polarise

ion for chloride ion

Answers that referto polarisation ofatoms score zero

Answers that referto electronegativityof ions score zero

2

The beryllium ion wosm l

and would polarise chloride ionsoducing sharing of electrons /(p

covalency) (1) An

electron transfer (1)

Allow Be2+ has a largee to sizech rg

ratio/large chargede sity

QuestionNumber


2.(d)(ii) .:Cl : Be: Cl:.. ..

Ignore shape and innercorrect

m xture of bothDimerIonic formula

.. .

electrons if

All dots or all crossesor iPolymer withcontinuation bonds 1

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QuestionNumber


3.(a)ydrogen bonds (1)

Linear around at least two H andwater shown as v shaped (1)

+

H and

O (1) must be shownacross at least one hydrogen bond

o ly two watermolecules shown max 2

marks

Blobs for O and H

provided correct +/

shown

Ignore a slip in partialcharges provided not partof hydrogen bond

If use O2H allowthird mark only

If any H bondshown betweentwo oxygens ortwo hydrogens

3

Diagram showing correct covalentand h

If n

H

O

H

H

O

H

H-

++

+

+ +

-

+H

-

O

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3.(b Each water can form more hydrogenbonds (than each hydrogen fluoride

So more energy is needed to break the

m (1)

d mark is stand alone unless wronge t

Each water moleculecan form two hydrogen

only

Each water moleculecan form four hydrogen

two

Intermolecular force

Just H bonds inwater are stronger

n t good enoughto score the mark

Any reference toen

mo

zer

2

)

molecule) (1)

hydrogen bonds in water/separatemolecules (hence higher boiling

erature)te p

n2int molecular force identified in firspart e.g. vdw

r

bonds, HF canform one

bonds HF can only form

for hydrogen bond

Is o

br aking covalentbo ds/bonds in the

lecule scores

o.

QuestionNumber


3.(c)(i)

HH

Musd e or dash or both. If three lines

drawn must not look planar

Ignore name unless planar

Ignore omission of +sign in diagram

1

O

H H HH

t attempt to draw as a pyramid

we g

QuestionNumber Correct Answer Acceptable Answers Reject Mark

3.(c)(ii)Mar ntly of (c)(i) 1Any number from 105 to 108 inclusive.

k independe

QuestionNumber


3.(c)(iii) Repulsion between the H3O+ and the H+ They are both cations

so repulsionORThey are both positive

so repulsion 1

+ +O

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Qu stioneNumber


4.(a Substance that can lower/reduce theoxidation number (of an element in

Ignore references to loss or gain ofelectrons unless contradictory.

Substance containingan element whose

incrrea

u s a decrease ine xidation numbert e

cule/species ita s with

oxid

ncr

The oxidationnumber goes down

defi ox

1

)

another substance) oxidation number iseased (in action)

A

ORCa seth oof hmolere ctORThe reducing agents

ation number

eases

nition of red

iQuestionNumber


4.(b)(i) 2ClO + 4H+ + ) Cl2 + 2H2O

Ignore state symbo d

Or

-2e on RHS1

multiples

()

2e(

ls an

QuestionNumber


4.(b)(ii) 2Cl- Cl2 + 2e()

symbols an

Or multiples

-2e() on LHS1

Ignore state d

QuestionNumber


4.(c) O Cl + 2H+ Cl2 + H2O

a alone not consequential on (b)

symbols and

Or multiplesCl +

St nd

Ignore state 1

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Qu stioneNumber


4.(d White/misty/steamy fumes

Mauvap

a solid

y two of above

e any yellow solid/

Ign ions e.g.get

lila

y) grey solid

White smoke

Ju id

2

)

ve/purple/violet/ (iodine)our/gas/fumes

Bl ck

An

Ignorbubbling/fizzing

ore non-visible observatting hot

c

(shin

st dark sol

precipitate

QuestionNumber


4.(e)(i) 2KC Or multipleslO3 2KCl + 3O21

QuestionNumber


4.(e)(ii) Oxidation n mbers a (1)

Cl OStart +5 -2d -1 0

ced

y en oxidised as

from

i tion number mark may be

p nations.

Penalise omission of reference tooxidation r2nd and 3rd marks are consequential onstated oxidation numbers.

Allow 5+, 2-, 1-

r n ofa sed and Cl asd ed scores (2)

provided oxidationnumber change is in thecorrect direction forboth even if actualnumbers wrong.

Cl5+ , Cl-1, O-2

3

u ll correct

En

orine reChas x

Allow V, -II, -I

ect identificatioCo rs oxidiO

re uc

l duo idation number decreases/

changes from +5 to -1 (1)

Ox goxidation number increases/changes

-2 to 0 (1)

Ox daawarded if included withinex la

or eduction once

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Qu stioneNumber


5.(a The ability of an atom/element/species to attract the electrons (1)

in a covalent bond/bond pair/sharedelectrons (1)

Power/extentinstead of ability

put of attract

Molecule

2

)(i)

lls toward/drawsins ead

QuestionNumber


5.(a)(ii) The molecule is symmetrical /tetrahedral (1)

So bond polarity/dipoles cancelsORcentres of positive and negativecharge coincide (1) stand alone

Diagrams showingvectors

Too small adifference in

electronegativity

Charge cancels

2

QuestionNumber


5.(a)(iii) Dispersion/Induced dipole /LondonORtemporary/instantaneous dipole

van der Waals/vdw Dipole-dipole

Hydrogen bond

1

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5.(b Ignore sig. figs UNLESS rounded to 1SF)(i)

700 g TMP = 700 (1) = 6.14 mol114

l s of oxygen = 12.5 x 6.14 (1) =

Volume of oxygen = 12.5 x 6.14 x 24=1842 dm3 (1)

Units essentialWorking must be checked i.e.3.07 x 25 x 24 = 1842 dm3 (2)3.07 x 12.5 x 24 = 921 dm3 (1)

OR228 g of TMP need 25 x 24 dm3 ofoxygen (1)

700 g of 700

Mo e76.75

TMP need 25 x 24 x of228

oxygen(1)

[Working must be checked]

1 3 to6.1

= 1842 dm3(1)

Units essential

1840/1800 dm3

8 0 if 6.14 rounded

Moles 2C8H18 = 700= 3.07

228

3

QuestionNumber


5.(b Ignore sig. figs UNLESS rounded to 1SF

CO = 8 x6.14 (1) =

Mass of CO2 = 8 x6.14 x44 = 2161 g (1)Units esse a ise if

already pen lised

OR

700g

)(ii)

Moles of 2 49.12

nti l but dont penal

a in (i)

228 g of TMP give 44 x 16 g CO2(1)

of TMP give 44 x 16 x 700 g228

O of C

Could be consequential on (i)

2160/2200

2

2

= 2161 g (1)

or 2147 / 2150 / 2100

if 6.14 rounded to 6.1

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Qu stioneNumber


6.(a Energy/Enthalpy/heat change per mole forthe (1)

one electron (per atom) (1)

o

quation given with a correctf ition (max 2)

Required instead ofchange

X(g) X+(g) + e() cascore last 2 marks

3

)

Removal of

Fr m 1 mole of gaseous atoms(1)

If wrong ede in

n

QuestionNumber


6.(b) g (1)

r

Increase indistance (of outermostelectron)/ gOR(increase in) shielding outweighs nuclearcharge (increase) (1)

e ref re

effective nuclear charge OR nuclearattraction

Electron at higher

Increase in shielding/screenin

Inc ease in nuclear charge/moreprotons/atomic number (1)

lar er atomic radius

e nces to:Ignor

energy level

3

QuestionNumber


6.(c)(i) Na:Mg:Almetallic (structure)

ture)

1

Siatomic (strucgiant

P:S:Cl:Arsimple molecularAll three correct 1 mark

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QuestionNumber

Correct Answer AcceptableAnswers

Reject Mark

6.(c)(ii) o g covalent bonds (1)

(throughout the lattice and lots ofenergy) need to break many bonds (1)2

str n

QuestionNumber

Correct Answer AcceptableAnswers

Reject Mark

6.(c)(iii) Aluminium supplies more electrons(per atom)/Al ion is more highlycharged/Al ion is smaller/ Al ion has ahigher charge density (1)

The (attractive) forces between thealuminium ions and the electrons arestronger/require more energy to breakthan in the case of sodium. (1)

Reverse for Na

Any reference tobonding other thanmetallic bond/sea of electrons/delocalised system 2

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jan 2007 unit 1 - MS