1.	(a)	(i)	transition element: has at least one ion with a partly filled d-orbital (1)
example showing electronic configuration with d orbital
as between d1 – d9 (1)
	complex ion: a central metal ion surrounded by ligands
with an example. (1)
ligand: molecule/ion with lone pair of electrons capable
of forming coordinate/ dative bonds to a metal ion (1)	4
 
(ii)	precipitation: equation (1)
colour of precipitate (1)
	ligand substitution: equation (1)
colour of substituted complex (1)
	redox: equation (1)
colour change (1)
	 The candidate clearly links observations to provide evidence
for two reactions discussed. (1)	7
 
(b)	complex ions:
octahedral example (1)
with 3-D diagram (1)
	tetrahedral example (1)
with 3-D diagram (1)
	square planar example (see also below) (1)
with 3-D diagram (1)
	stereoisomerism:
cis-trans example, e.g. Ni(NH3)2Cl2; platin with 3-D diagram (1)
optical example, e.g. Ni(en)32+ (1)
with 3D diagrams (1)
	 The candidate clearly links features on the diagrams with a
characteristic of the stereoisomerism involved (1)	Max: 9
[20]

2.	Oxidation because oxidation state of Hg changes from 0 to +2 so oxidation (1)
Reduction because oxidation number of O changes from –1 to –2 (1)
	Or
	Correct identification of all the oxidation numbers (1)
Correct identification of oxidation and reduction (1)	2
Allow ecf for the identification of oxidation and reduction from wrong oxidation numbers
[2]

3.	Does not have an incomplete set of d electrons / does
not have a partially filled d orbital / does not have a
partially filled d sub-shell / ora (1)	1
Allow use of 3d
[1]

4.	(i)	(1s22s22p6)3s23p63d6 (1)	1
 
(ii)	Octahedral shape with some indication of three dimensions (1);
	Bond angle 90° (1)	2
Allow use of wedges and dotted lines to indicate three dimensions
Allow three dimensions if at least two bond angles of 90o are shown that clearly demonstrate 3D
If two different bond angles do not award bond angle mark
 
(iii)	Green / olive green / dark-green / green-blue ppt (1)
Allow solid instead of precipitate
Allow solid or precipitate to be awarded from the state symbol in Fe(OH)2(s)
	Fe2+(aq) + 2OH–(aq) → Fe(OH)2(s) (1)	2
[5]

5.	(i)	MnO2 + 4H+ + 2Fe2+ → Mn2+ + 2H2O + 2Fe3+ (1)	1
Ignore state symbols

(ii)	Moles of Fe2+ that reacted with MnO2 = 0.02 – 0.0123 = 0.0077 (1)
Allow ecf within question
	Mass of MnO2 = 0.00385 × 86.9 = 0.335 (1)
% purity = 66.4% (1)
Allow 66.4 – 66.5
	Alternatively
	Moles of MnO2 in 0.504 = 0.00580
So moles of Fe2+ that should react with this is 0.0116 (1)
Moles of Fe2+ that reacted with MnO2 = 0.02 – 0.0123 = 0.0077 (1)
% purity = 66.4% (1)	3
[4]

6.	(a)	(i)	+3	1
(ii)	Cis and trans forms drawn in 3-D (only award these
marks if C has been chosen)	2
(iii)	Type of isomerism is cis-trans/geometric	1
 
(b)	(i)	(concentrated) hydrochloric acid/sodium chloride/
Other suitable named ionic chloride but not just chloride or Cl–	1
(ii)	Ligand substitution / ligand exchange	1
[6]

7.	(i)	Decolorised / add starch which is decolorised
Allow blue/black → white or brown → white	1
Do not allow colourless
 
(ii)	moles S2O32– = 23.20 × 0.100/1000 = 0.00232 moles	1
Cu2+ ≡ S2O32– / moles Cu2+ = 0.00232 moles	1
But 25 cm3 of original = 10 × 0.00232 = 0.0232 moles	1
Concentration of original = 1000 × 0.0232 / 25	1
 
(iii)	Because concentration of Cu2+ is less than 1 mol dm–3 / less than standard	1
equilibrium moves to left (reducing +ve value of E)	1
[7]

8.	(i)	1s22s22p63s23p63d5 (1)	1
(ii)	Has an incomplete set of d electrons / partially
filled d sub-shell / partially filled d orbital (1)	1
Allow partially filled d shell
[2]

9.	(i)	Has a (lone) pair of electrons that can be donated / lone pair that can form
a dative bond / pair of electrons that can form a coordinate bond (1)	1
 
(ii)	3D diagram of octahedral structure (1);
Bond angle 90° (1)	2
Name
octahedral must be present to score two marks
Allow use of wedges and dotted lines to indicate three dimensions
Allow three dimensions if at least two bond angles of 90° are shown that clearly demonstrate 3D
If two different bond angles do not award bond angle mark
[3]

10.	(i)	Brown / red-brown / foxy-red / rusty / orange ppt (1)	1
Allow solid instead of precipitate
Allow state symbol (s) for precipitate
 
(ii)	Fe3+(aq) + 3OH–(aq) → Fe(OH)3(s)
Correct equation (1)
State symbols for the correct formulae even if
spectator ions are present (1)	2
Allow equations using the hydrated iron(III) ion
[3]

11.	Fe2O3 + 3Cl2 + 10OH– → 2FeO42– + 5H2O + 6Cl– (2)	2
Allow one mark if electrons shown
Allow one mark if correct reactants and products but not balanced
[2]

12.	Correct Mr for Fe2O3, 159.6, and of Na2FeO4,165.8 (1)
Moles of Fe2O3 = 0.00627 (1);
Mass of Na2FeO4 = 2.08 (1);
Percentage = 21.6 or 21.7 (%) (1)	4
Allow full marks for correct answer with some working
Answer must have 3 sig figs
Allow ecf from wrong moles or wrong mass
[4]

13.	Oxidation state of iron changes from +6 to +3 so is reduction (1)
	Oxidation state of oxygen changes from –2 to 0 so is oxidation (1)
To get the two marks for oxidation states marks any other oxidation state quoted must be correct.
Maximum one mark if any other oxidation number given is wrong
	OR
	Oxidation state of iron changes from +6 to +3 and
oxidation state of oxygen changes from –2 to 0 (1)
	Iron is reduced and oxygen is oxidised (1)	2
Allow ecf from wrong oxidation states
[2]

14.	(i)	(Oxidised to) iodine so a brown (solution) formed /
Fe3+ formed which is yellow or orange / Fe2+ formed which is green (1)	1
Allow red/brown or orange
 
(ii)	Nitrogen / N2 (1)	1
Allow any correctly named oxide of nitrogen / correct formulae / HNO3 etc.
[2]

15.	20 cm3 of 0.100 mol dm–3 VO2+ = 0.002 moles	1
0.002 moles VO2+ = 0.0004 moles MnO4–	1
0.0004 moles MnO4– are in 16.0 cm3	1
[3]

16.	(a)	Ligand able to donate two lone pairs	1
to form dative covalent / co-ordinate bonds	1
 
(b)

	3-D diagram with three ethanedioate ligands used	1
correct bonding between ligands and Cr3+	1
correct charge on ion (3–)	1
(Accept O ── O as minimum for ethanedioate ion)
[5]

17.	stereoisomers have same structural formula but a
different arrangement in space	1
		2

	Diagrams of cis and trans isomers

Diagrams showing two optical isomers	2
(If diagrams are wrong / not used give 1 mark for mention
of cis/trans and optical isomerism)
H2O at 90°/ adjacent in cis / 180° / opposite in trans (not from diagram)	1
Optical isomers are non-superimposable mirror images	1
	Quality of Written Communication:
At least three of the following key words used in context:
non-superimposable, mirror images, optical, cis/trans, geometric,
plane polarised, rotate, chiral, asymmetric	1
[8]

18.	Add (aqueous) sodium hydroxide which will give a brown/rusty ppt (1)	1
Allow solid for precipitate or (s) in equation
Allow Use aqueous thiocyanate ions which gives a (blood) red colouration
[1]

19.	(i)	Cr2O72– + 14H+ + 6Fe2+ → 2Cr3+ + 7H2O + 6Fe3+
Correct reactants and products (1);
Correct balancing (electrons cancelled out) (1)	2
 
(ii)	Moles of dichromate(VI) = 3.53 × 10–4 (1);
Moles of iron(II) = 2.12 × 10–3 (1):
Moles of impure iron(II) sulphate = 2.36 × 10–3 (1);
Percentage purity = 89.8 / 89.8 – 90.0 (1)	4
Allow alternative working out via mass instead of moles e.g. mass of iron in hydrated FeSO4 from percentage composition compared to mass of iron from moles of iron(II).
Allow ecf throughout unless percentage is above 100%
[6]

20.	(a)	(i)	(Blue to) yellow (solution) / (blue to) green (solution) (1)	1
(ii)	Lone pair on chloride ion (1);
Donated to copper(II) ion (1)	2
Allow dative bond / coordinate bond (1)
Allow marks via a diagram that must show lone pairs and the dative bond
 
(b)	(Light) blue precipitate / blue solid (1);
With excess (dark) blue solution (1)	2
Not just goes blue
[5]

21.	Any three from
Ammonia molecule 1 lone pair (and 3 bond pairs) (1);
Ammonia ligand 4 bond pairs / lone pair is now a bond pair /
ligand does not have a lone pair (1);
Lone pairs repel more than bond pairs (1):
In complex equal repulsion between electron pairs (1)	3
Not bonds repel / atoms repel
[3]

22.	(i)	6	1
(ii)	Species with (lone) pair of electrons	1
Capable of being donated / forms a dative covalent
bond / co-ordinate bond to a metal ion.	1
(allow suitable diagram)
[3]

23.	(i)	[Co(H2O)6]2+ is octahedral
[CoCl4]2- is tetrahedral (both needed for 1 mark)	1
(ii)	pink to blue	1
(iii)	Ligand substitution / exchange/displacement	1
[3]

24.	(a)	(i)	1 mark for correct 3-D diagram of cis isomer	1
1 mark for correct 3-D diagram of trans isomer	1
	(Allow planar diagrams if two appropriate 90° angles are shown)
	Allow any suitable 3-D diagrams. Possibilities to include:

(ii)	Geometric / cis – trans	1
 
(b)	1 mark for using cis isomer	1
1 mark for correct 3-D diagrams which are mirror images of each other.	1
	(If all diagrams are drawn as non-3d do not penalise in (b))
	Allow any suitable 3-D diagrams such as:

[5]

25.	(i)	Brown solution/brown precipitate/black solid
Add starch to get blue / black colour	1
 
(ii)	Titration / volumetric analysis	1
using sodium thiosulphate(with starch indicator)	1
(allow from equation)
	I2 + 2S2O32– → 2I– + S4O62–	1
	1 mol Cr2O72– = 6 mols S2O32–	1
[5]

26.	(a)	Zn2+ is 1s22s22p63s23p63d10 and
Cu2+ is 1s22s22p63s23p63d9 (1);
Allow Zn2+ [Ar]3d10 and Cu2+ [Ar]3d9
	Copper has at least one ion with an incomplete filled d-orbital
(zinc does not) / copper(II) ion has an incomplete set of
d electrons (zinc ion does not) / copper(II) ion has an
incomplete d sub-shell (zinc ion does not) / ora (1)	2
 
(b)	Cu2+ compounds are coloured but Zn2+ compounds are not (1);
Cu2+ compounds may be catalytic but Zn2+ compounds are not (1)	2
Allow Cu2+ forms complexes but Zn2+ does not
Allow correct chemistry of Cu2+ compared to Zn2+ e.g. Cu2+ and NaOH gives blue ppt but Zn2+ gives white ppt (that redissolves in excess)
[4]

27.	Moles of hydrogen = 3.17 × 10–3 / moles of zinc = 3.17 × 10-3 (1);
Not 3 × 10–3
	Mass of zinc = 0.207 g / moles of zinc × 65.4 (1);
Not 0.2
	Percentage of copper = 83.2 (1)	3
Allow ecf
Final answer must be to 3 or 4 sig figs
Penalise significant figures just once
Allow values between 82.9–83.2
[3]

28.	(i)	Cu → Cu2+ + 2e- / Cu – 2e- → Cu2+ (1)	1
(ii)	2Cu + O2 + 4H+ → 2Cu2+ + 2H2O (1)	1
Allow any correct multiple
Allow ecf from (a)(i)
[2]

29.	Mr of [Cu(CH3COO)2]2.Cu(OH)2 = 460.5 (1)
Allow ecf from wrong Mr
	Molar ratio [Cu(CH3COO)2]2.Cu(OH)2 : H2O is 0.182 : 0.906 (1)
x = 5 (1)	3
Not full marks for 5 with no working out
[3]

30.	Ligand substitution
	Suitable example e.g. reaction of thiocyanate ions with hexaaquairon(III)
to give [Fe(H2O)5(CNS)]2+ (1);
Observations e.g. formation of a blood-red colour (1)
Suitable equation e.g.
[Fe(H2O)6]3+ + CNS– → [Fe(H2O)5(CNS)]2+ + H2O (1)
Suitable example can be awarded from an equation
Equations do not need state symbols
	Precipitation
	Suitable example e.g. reaction between (aqueous) iron(II) chloride
with (aqueous) sodium hydroxide (1);
Observations e.g. formation of a green precipitate / formation of a green solid (1)
Suitable equation e.g. Fe2+(aq) + 2OH–(aq) → Fe(OH)2(s) (1)
Precipitate can be awarded state symbol in equation
 
	Redox
	Suitable example e.g. oxidation of iron(II) chloride by chlorine to
make iron(III) chloride (1)
Observation e.g. green solution becomes yellow / rust solution (1)
Suitable equation e.g. 2FeCl2 + Cl2 → 2FeCl3 (1)
Other examples could include iron and chlorine to make iron(III) chloride / iron and HCl to make FeCl2 / MnO4– and Fe2+ to make Fe3+
	And QWC
	One mark for correct spelling, punctuation and grammar in at least two sentences (1)	10
Answer must address the question
[10]

31.	(a)	1s22s22p63s23p63d8 (Do not accept [Ar]3d8)	1

(b)	(i)	Ring around O–	1
Ring around N	1
(Accept ring around O of C=O as an alternative to O–)
(ii)	Lone pair (of electrons) / non-bonding pair	1
[4]

32.	(a)	(i)	Number of dative bonds / co-ordinate bonds formed with the
transition metal (Do not accept number of ligands but allow
number of lone pairs bonded to….)	1
 
(ii)	Square planar	1
 
(b)	(i)	Ligand substitution	1
(ii)	x = –2	1
y = 0	1
 
(c)	(i)	cis isomer drawn	1
trans isomer drawn	1
(ignore any charges)

(ii)	cis / trans or geometric	1
(iii)	Binds with DNA (not binds with cell)	1
Prevents replication/prevents cell dividing/prevents tumour
growth (do not allow kills cell)	1
[10]

33.	(a)	Moles V2+ = 25.0 × 0.100 / 1000 = 0.0025 mols	1
Moles MnO4– = 30.0 × 0.0500 / 1000 = 0.00150 mols	1
1 mole of MnO4- changes its Oxidation State by 5 to change
the Oxidation State of 1.67 moles of V2+	1
Oxidation State of V2+ changes by 5 / 1.67 = 3	1

(b)	3MnO4– + 5V2+ + 3H2O → 3Mn2+ + 5VO3– + 6H+
(1 mark for correct species, 1 mark for balanced)	2
[6]

34.	(a)	1s22s22p63s23p63d5 (1);
Has an incomplete set of 3d electrons (1)	2
Allow 3d orbitals are not completely occupied / incomplete 3d sub-shell
Allow has half-filled d orbitals
 
(b)	Any two from
Variable oxidation state / variable valency (1);
Act as catalysts (1);
Form complexes / form complex ions (1);
Form coloured compounds (1)	2
Not high melting point / good thermal and electrical conductors / high density etc
 
(c)	Iron (II) ions give a green ppt (1);
Iron (III) ions give an orange-rust ppt (1)	2
Precipitate must be used once
Allow solid instead of ppt
 
(d)	4Fe2+ + O2 + 4H+ → 4Fe3+ + 2H2O
Correct reactants and products (1);
Correct balancing (1)	2
[8]

35.	(i)	Copper may react with potassium manganate(VII) /
iron(III) ions formed in titration may be reduced back to
iron(II) ions by the copper (1)	1
 
(ii)	MnO4– gains electrons and is reduced / Mn oxidation
state changes from +7 to +2 so it is reduced (1);
Fe2+ loses electrons and is oxidised / Fe oxidation state
changes from +2 to +3 so it is oxidised (1)	2

(iii)	Moles of MnO4– = 4.50 × 10–4 (1);
Moles of Fe2+ = 5 × moles MnO4– / 2.25 × 10–3 (1);
Mass of Fe = moles of Fe2+ × 55.8 / 0.1256 (1);
Percentage = 18.6 % (1)	4
Allow answers that use 56 for Ar of Fe this gives 18.7
Allow ecf
[7]

36.	(a)	(Pale blue solution) to a (light) blue ppt (1);
with excess dark blue solution (1)	2
 
(b)	Octahedral shape with clear indication of 3D either by
construction lines or wedges etc (1);
90° (1)	2
Ignore mistakes with the ligands question focuses on octahedral and the bond angle
[4]

37.	Water molecule 2 lone pairs (and 2 bond pairs) (1);
Water ligand 1 lone pair and 3 bond pairs / lone pair is now
a bond pair / water has one less lone pair when it is a ligand (1);
Lone pairs repel more than bond pairs (1)	3
Not atoms repel
[3]

38.	(i)	Central ion surrounded by molecules/ions/ligands	1
(ii)	Molecule/ion with a lone pair of electrons	1
Able to form a dative covalent or co-ordinate bond /
which can be donated	1
[3]

39.	(a)	Two lone pairs/ able to form two dative covalent / co-ordinate bonds	1
(b)	Stereoisomerism – same atoms with same order of bonds but a
different spatial arrangement / same structure but different
arrangement of atoms	1
Both isomers drawn for cis / trans	2
Both isomers drawn for optical (must be mirror images)	2
(all diagrams to show 3-D arrangement)
Enantiomers/non superimposable mirror images	1
Rotate plane polarised light in opposite direction by same
number of degrees (any two for 1 mark)	1
[8]

40.	(i)	Cr2O72– + 14H+ + 6I–  2Cr3+ + 3I2 + 7H2O
All species correct (ignore electrons for this mark)	1
Equation balanced (penalise if electrons not cancelled out)	1
 
(ii)	Brown colour disappears	1
S2O32– reacts with I2 (to form colourless I–)	1
Green colour remains due to Cr3+ (must say what gives green colour)	1
[5]

41.	moles HCl in 23.2 cm3 = 0.200 × 23.2/1000 = 4.64 × 10–3 (1)
moles B in 25 cm3 = moles HCl = 4.64 × 10–3 (1)
moles B in 250 cm3 = 4.64 × 10–3 × 10 = 4.64 × 10–2 (1)
4.64 × 10–2 mol B has a mass of 4.32 g
molar mass of B = 4.32/4.64 × 10–2 = 93 g mol–1 (1)
93 – 16 = 77 (1)
Therefore B is phenylamine / C6H5NH2 (1)	6
There may be other valid structures that are amines. These can be credited provided that everything adds up to 93.
Answer could be a primary, secondary or tertiary amines.
[6]

42.	Transition element
Cu2+ 1s22s22p63s23p63d9 (1);
Transition elements have one oxidation state that has an
incomplete set of 3d electrons / have one ion with a half-filled 3d orbital (1)
Allow has at least one half-filled d orbital / partially filled 3d sub-shell
	Complex ion
Example of a copper complex ion e.g. [Cu(H2O)6]2+ or CuCl42– (1);
Diagram of the copper complex showing three
dimensions e.g. use of wedges or dotted lines (1);
Correct bond angle to match the complex / correct name
of the shape of the complex (1);
If a copper complex that does not exist is used then first three marks not available
If a correct iron complex is given then example mark cannot be awarded
Allow square planar where appropriate
 
	Ligand is an electron pair donor (1);
Copper(II) ion is an electron pair acceptor (1);
Dative bond exists between ligand and the copper(II) ion (1)
Electron pair donor, electron pair acceptor and dative bond marks can awarded from an appropriate diagram
	Properties
Several oxidation states e.g. copper has +1 and +2 or iron has +2 and +3 (1);
Ignore copper has a +3
Ignore iron has a +6 oxidation state
	Forms coloured compounds e.g. copper(ii) chloride is
green or iron(II) sulphate is pale green (1);
Element or compound has catalytic properties
e.g. Iron is a catalyst in the Haber process (1)	11

	Quality of written communication
	Use of technical terms – at least three terms from the following list are
used in the correct context
•	ligand
•	dative bond
•	coordinate bond
•	tetrahedral
•	square planar
•	octahedral
•	oxidation (state)
•	catalyst
•	electron pair
•	lone pair
•	orbital
•	sub-shell (1)	1
Put a ring around the technical terms
[12]

43.	(a)	(i)	Zinc	1
 
(ii)	Coins + resist corrosion (not rusting) / hard wearing
Or statues + resist corrosion/ attractive patina
Or electrical connections + good conductor
Or musical instruments + attractive / sonorous
Or plumbing fixtures + hard / corrosion resistant	1
 
(b)	(i)	Sodium carbonate/sodium hydroxide/other suitable
named alkali (accept correct formulae)	1
Do not accept ‘alkali’ on its own
 
(ii)	Starch	1
 
(iii)	Just before the end point/when solution turns pale straw	1
 
(c)	(i)	0.002 mol	1

(ii)	One (1)	1
(iii)	0.002 mol	1
(iv)	0.002 mols Cu2+ contains 0.002 × 63.5 g of Cu = 0.127 g	1
250 cm3 of solution contains 10 × 0.127 g = 1.27 g	1
% Cu = 1.27/1.65 × 100 = 77.0%	1
(Allow 76.9-77.0; allow ecf)
[11]

44.	(a)	Number of coordinate / dative covalent bonds attached
to metal ion / number of lone pairs accepted (not number of ligands)	1
 
(b)	(i)	[Co(H2O)6]2+ is octahedral; [CoCl4]2– is tetrahedral
Drawings must be 3 dimensional
	Acceptable shapes for [Co(H2O)6]2+ include:

	Acceptable shapes for [CoCl4]2– include
	2
 
(ii)	Pink → blue	2
 
(iii)	Add water.
(Allow other suitable suggestions, e.g. add lead nitrate to
precipitate Cl– as PbCl2)	1
[6]

45.	(i)	Cis platin	1
(ii)	Binds to DNA	1
Prevents cell from replicating / cells die	1
[3]

46.	(Cis/trans) + Examples (must be 3-d drawings)	2
Correctly labelled as cis and trans (allow this mark if diagrams are planar)	1
Cis has same atoms at 90° + Trans has same atoms at
180° (need reference to bond angles for mark)	1
(Optical) + examples (must be 3-d drawings)	2
Rotate plane polarised light (by same number of
degrees) in opposite directions	1
Non-superimposable mirror images	1
NB If use H3N CH2 CH2 NH3 penalise only once
 
	Any example which show the principle of cis/trans isomerism and optical
isomerism are fine but, all diagrams must be 3-d. The shapes shown in the
previous question are allowed for octahedral or tetrahedral. For square planar
complexes used to illustrate cis/trans isomerism the following illustrations
are fine. For optical isomerism, there must be a mirror line and the isomers must
be non-superimposable object/mirror images.

	QWC – to be awarded for the correct use of scientific
terms, to include at least 3 of the following:
Cis & trans, optical, plane, polarised, non-superimposable,
mirror images, geometric, bidentate,
ligand, octahedral, square planar, tetrahedral	1
[9]