transition metal complex marksheme

8/11/2019 Transition Metal Complex Marksheme

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1. (a) +1 or Cu+ (1)

1s2 2s

2 2p

6 3s

2 3p

6 3d

10 or Ar 3d

10 (1)

3d sub-shell is fully filled (1) 3

(b) Cu C1

– 2

4 (1)

Tetrahedral (1) 2

(c) !idisi"# a#e"t (1) 1

(d) 2e –

+ 2$+ + $22 → 2$2 (1) 1

(e) CuC1

– 2

4 + 6$2 → %Cu ($2)6&2+

+4C1 –

(1)

'i#a"d or electro" pair do"or (1)

or 'eis base 2[9]

2. (a) electro" pair acceptor (1) or lo"e

proto" do"or (1) 2

(b) (i) AlCl3 + 6$2 → %Al ($2)6&3+

+ 3Cl –

(1)

(ii) %Al ($2)6&3+

+ $2 (or a"y base) (1)

→%Al($) ($2)*&2+

(1) + $3+ (1) (or proto"ated base)

(iii) AlCl3 + Cl –

→ %AlCl4& –

(1)

or %Al($2)

6&3+

+ 4Cl –

→ %AlCl4& –

+ 6$2 (1) 3

(c) (i) efferesce"ce (1)

bro" ppt (1)

,e($)3 ($2)3 or ,e($)3 (1)

(ii) #ree" (1) solutio" (1)

(i#"ore e"tio" of ppt)

%Cr($)6&3–

(1)

or %Cr($)4($2)2& – 6

[11]

3. (i) replacee"t of o"e li#a"d by a"other (1)

(ii) %Ti ($2)4Cl2&+ + 2 $2 → %Ti ($2)6&

3+ + 2Cl

– (1)

(iii) cha"#e of li#a"d (1) 3

[3]



4. %Co($2)6&2+

(1)

A#Cl (1)

%A#(.$3)2&+ (1)

%CoCl4&2–

(1)

%Co($)2($2)4& or Co($)2 (1)

%Co(.$3)6&2+

(1)

%Co(.$3)6&3+

CoCl2 or CoCl2/ x$2 (1)

[8]

5. (a) A shared electro" pair or a coale"t bo"d (1)

oth electro"s fro o"e ato (1)

OR when a Lewis base reacts with a Lewis acidMark points separately 2

(b) Br ønsted-Lowry acid A proto" or $+ do"or (1)

Not H3O+

Lewis acid A lo"e or electro" pair acceptor (1) 2

(c) To atos or to poi"ts of attache"t (1)

ach do"ati"# a lo"e electro" pair (1)OR or!s " #1$ co%ordinate bonds #1$OR donates two #1$ pairs o electrons #1$

2

(d) Change in co-ordination number 6 to 4 (1)

Reason for change chloride li#a"ds are lar#er tha" ater li#a"ds (1)OR &reater rep'lsion between chloride li&ands(O NO) allow chlorine or *l

2

(e) ae "uber (1) a"d sae type of bo"ds (1) broe" a"d ade 2

(f) Cl.$3C$2C$2 .$3Cl (1)

OR #NH3*H"*H"NH3$"+

"*l

,llow *"H1-N"*l" and NH3*l*H"*H"NH3*l

1[11]

6. (a) octahedral (1) 1

(b) %,e($2)6&3+

+ $2 → %,e($)($2)*&2+

+ $3+ (1)

(or a"y base)

(proto"ated base)

1

(c) %,e($)($2)*&2+

or %,e($)2($2)4&+

(1) 1



(d) HNO3 ≡ H3O+ addition or increases concentration of acid (1)

reverses equilibrium or forms [Fe(H2O)6]3+

(1) 2

(e) cha"#e of li#a"d (1)

cha"#e of shape or coord" "uber (1) 2

(f) Identity $2 (1)

,e($)3($2)3 or ,e($)3 (1)

35# + 2%,e($2)6&3+

→ 35#2+

+ 3$2 + 2%,e($)3($2)3& (1)

or 2 separate e"s each correct but "ot "ecessarily cobi"ed

or 5# + %,e($)($2)*&2+

→ 5#2+

+ $2 + %,e($)3($2)3& 3

[1-]

7. (a) 3d7

1

(b) %Co($2)6&2+

1

8i" 1

(c) (i) %Co(.$3)6&2+

1

8ale bro" or stra 1

(ii) %Co($2)6&2+

+ 6.$3 → %Co(.$3)6&2+

+ 6$2 1

(d) %Co(.$3)6&3+ 1A" o!idisi"# a#e"t 1

[8]

8. (a) o!idatio" state of . i" Cu(.3)2 +*9 1

o!idatio" state of . i" .2 +49 1

o!idatio" product o!y#e"9 1

(b) copper-co"tai"i"# species %Cu($2)6&2+

9

1shape octahedral9

1

(c) (i) precipitate Cu($2)4($)2 or Cu($)2 or "ae9

1

euatio" %Cu($2)6&2+

+ 2.$3 → Cu($2)4($)2 + 2.$4+

:

.$3 + $2 → .$4+ + $

–

a"d

%Cu($2)6&2+

+ 2$ –

→ Cu($2)4($)2 + 2$29 1



(ii) .$3 accepts a proto"9 1

(d) (i) ide"tity %Cu(.$3)4($2)2&2+

9 1

colour deep blue9 1

euatio"

Cu($2)4($)2 + 4.$3 → %Cu(.$3)4($2)2&2+

+ 2$2 + 2$ –

9 1

(ii) .$3 is a" electro" pair do"or9 1

(e) ide"tity %CuCl4&2–

9

1

colour yello-#ree"9

1

shape tetrahedral91

(f) (i) ;s2 2s

2 2p

6 3s

2 3p

6 3d

10 9 1

(ii) role of Cu a reduci"# a#e"t9 1[1.]

9. (a) A Cr($2)3($)3 (or Co($)3 1

B C2 1

2%Cr($2

)6

&3+

+3C3

2– → 2%Cr($

2

)3

($)3

& + 3C2

+3$2

1

(or gives 2Cr(O!" # "CO2 # $ 2O!

(b) (i) .a$

(or <$) 1

(ii) +6

(or 6 or +=; or =;) 1

(iii) $22

(or.a22 or a2) 1

%Cr($)6&3–

+ 2$ –

→ Cr42–

+4$2 + 3e –

1

(or %Cr(O!& '" → CrO)

2 #2 2O # 2

# # "e

!



(c) (i)

$ .2

3 +

$ 2

.

.$ 2 $ .2

C r

. $ 2

. $ 2

At least o"e $2 .C$2C$2 .$2 ith correct structure a"d bo"di"#

to Cr ia . 1

6 co–ordi"atio" ith 3 e" dra" correctly 1

Correct 3+ char#e 1

(*ar+ inde,endenty but must not have & monodentate igands!

(ii) ae (or siilar) type of bo"ds broe" a"d ade 1ae "uber of bo"ds broe" a"d ade

(or sae co–ordi"atio" "uber) 1

(iii) "tropy cha"#e (or ∆.! is positie

(or i"crease i" disorder) 1

ecause there are ore product particles tha" reacta"t particles 1

(d) %Cr($2)6&2+

1

:educi"# a#e"t 1

(mar+ inde,endenty!



(e) (i) Etanal (or !H3!HO) (not !H3!OH) "

(ii) tha"oic acid (or correct forula) 1[18]

10. 8ale #ree" solutio" 1

>ree" precipitate fored 1;"soluble i" e!cess ao"ia 1

uatio"++

+→+ 424232

62 2.$&($))%,e($2.$&)%,e($e/#/pecies 1

ala"ce 1

5a! 4

/B 0ow e1uations with 2O and O –

if reaction of 2O with

/ 3 aso given

[/]

11. (a) (i) A" ato io" or olecule hich ca" do"ate a lo"e electro" pair 1

(ii) A ce"tral etal io"?species surrou"ded by co-ordi"ately bo"ded li#a"ds 1

or io" i" hich co-ordi"atio" "uber e!ceeds o!idatio" state

(iii) The "uber of co-ordi"ate bo"ds fored to a ce"tral etal io" 1

or "uber of electro" pairs do"ated or do"or atos

(b) (i) 0ow the reverse of each substitution

%Co($2)6&2+

+ 6.$3 → %Co(.$3)6&2+

+ 6$2

Cople! io"s 1

ala"ced 1

0ow ,artia substitution

(ii) %Co($2)6&2+

+ 4Cl –

→ CoCl – 24 + 6$2

Cople! io"s 1

ala"ced 1

or 2O or / " or C 2O ( 2

) by C

e#/ (iii)6$&)%Co(C3C&)%Co($ 2

4342

242

262 +→+

−−+

Cople! io"s 1

ala"ced 1

0ow a substitution exce,t

(i! / " by 2O

(ii! more than 2C

substituted for / " or 2O

e#/ (i)6$%Co(@TA)&@TA&)%Co($ 2

24262 +→+

−−+

Cople! io"s 1

ala"ced 1

or 2O or/ " by−2

)2OC and "

/ or −

C- by−4

@TA

(c) (i) %,e($2)6&2+

1

(ii) ,e($)2 or ,e($)2($2) x here x 0 to 4 1

(iii) ,e2+

is o!idised to ,e3+

or ,e($)3 1

y o!y#e" i" the air 1



[10]

12. (i) Cobat-containing s,ecies %Co($2)6&2+

(1)

reci,itate M Co($2)4($)2 or Co($)2 (1)

(ii) %Co(.$3)6&2+

(1)

(iii) 3y,e of reaction Co2+ o!idised to Co3+ (1)

Reactant res,onsibe !y#e" (1)

*[0]

13. (a) (i) Cu 3d10

4s1 ? 4s

1 3d

10) (1)

) ar i"depe"de"tly

Cu2+

3dB

) (1) 2

(b) (i) coordi"ate ? datie ? datie coale"t (1) 1

(ii) octahedral (1)

tetrahedral ? suare pla"ar (1) 2

(iii) a"y blue "ot blue-#ree" or #ree" (1)

to yello ? #ree" (1) 2

(c) (i) a"y blue precipitate

royal ? darer ? deep blue solutio" "ot ust blue (1)

if solutio" said to for before precipitate the" 0 ars 2

(ii) %Cu(.$3

)4

($2

)2

&2+

o"ly (1) 1

[1-]

14. (a) (i) dissoles i" acids a"d alalis (bases) (1)

or reacts ith

or behaes as

(ii) (Al species correct (1)?bala"ce (1))

41uation 5 %Al($)3($2)3& (or Al($)3) + 3 $3 (or $+) →

%Al($2)6&3+

+ 3$2 [2]

41uation 2 %Al($)3($2)3& + $ – → %Al($)4($2)2& – + $2 [2]

or %Al($)4& –

or %Al($)6&3–

*

(b)

C l ? 0 r r e a # e " ts t a t e d

f i l t e r o f f A # Dd i s s o l + e i " . $

o r . a 3 o r < C .

( 1 )( 1 )

( 1 )2 22 23

3

3

3 2

3

3

3

D 3 . $f i l t e r o f f

A l ( $ )o r p r e c i p i t a t e s

( 1 )( 1 )

( 1 )

D 3 . a $f i l t e r o f f A #

d i s s o l + e i " . $o r . a 3

o r < C .

o r $ .

( 1 )

( 1 )

( 1 )

– –

%A#(.$3)2&+ %A#(23)2&

3– %A#(C.)2&

– %A#($2)2&

+ (1)



li"ear (1) *[1-]

15. (i) 6eow-green s,ecies %CuCl4&2–

(1)

.ha,e tetrahedral (1)

Oxidation state of co,,er +2 (1)

(ii) %CuCl4&2–

+ 6$2 %Cu($2)6&2+

+ 4Cl –

(1)

(iii) Cu+ has full d-shell (%Ar&d

10) (1) *

[0]

16. (a) ,e (1)

%,e($2)6&2+

(1)

%,e($)2($2)4& (1)

%,e($)3($

2)

3& (1) 4

(b) Cu (1)

%Cu($2)6&2+

(1)

%CuCl4&2–

(1)

%Cu($)2($2)4& (1)

%Cu(.$3)4($2)2&2+

(1) *

[9]

17. (a) (i) %Cr($2)6&3+

+ $2 → %Cr($2)*($)&2+

+ $3+ (1)

OR [*r#H"O$]3+

[*r#H"O$0#OH$]"+

+ H+

(O NO) allow reactions with bases other than water

,llow loss o 'p to " H+

(ii) Cr 3+

is saller tha" Cr 2+

(1)

OR *r 3+

has a &reater char&e density or char&e to si2e ratio

Cr 3+

is ore polarisi"# (1)OR draws electron density ro! oy&en

o ore E$ bo"ds brea (eae"ed) (1)Ma " ro! three

3

(b) (i) Cr($2)3($)3 or Cr($)3 or Cr($)3 ! $2 here ! 1 2 or 3 (1)

OR na!e chro!i'! #444$ hydroide

(ii) ase or electro" pair do"or or proto" acceptor (1)NO) alkali5 i&nore n'cleophile b't penalise 6li&and7

(iii) 7as evoved C2 or "ae (1)

41uation

3C32–

+ 2%Cr($2)6&3+

→ 2%Cr($2)3($)3& + 3C2 + 3$2 (1)

N i separate e:'ations or *O3"

and *r 3+

#a:$ &i;en an

o;erall e:'ation !'st be ded'ced

4[9]



18. (a) (i) >aCl3 + 6$2 → %>a($2)6&3+

+ 3Cl –

(1)

(ii) 2 – * (1)

>a 3+ io" or hi#h cha"#e de"sity (1)

hydrolysis or polarises $2 or –$ bo"d (1)

or correct e" shoi"# $3+ foratio" (2) 4

(b) (i) efferesce"ce (1)

ppt (1)

,enaise if cooured

%>a($2)6&3+

+ 3$2 → %>a($)3($2)3& + 3$3+ (1)

2$3+ + C3

2– → C2 + 3$2 (1)

or 2%>a($2)6&3+

+3C32– →2%>a($)3($2)3&+3C2 + 3$2 (2)

(ii) ppt (1)

not if cooured

dissoles i" e!cess (1)

%>a($2)6&3+

+ 3$ –

→ %>a($)3($2)3& + 3$2 (1)

or %>a($2)6&3+

+ 3$2 (as aboe) the" $3+ + $

– → 2$2

%>a($)3($2)3& + $ –

→ %>a($)4($2)2& –

+ $2

or + 3$ –

→ %>a($)6&3–

+ 3$2

or +$ –

→ %>a($)4& –

+ 3$2

or >a($)3 + $ – → %>a($)4& – etc (1) F

[1"]



19. (a) electron donor (1)

electron #air acce#tor (1) 2

(b) C$3C$2C$2C$2C$3 (1)

"o lo"e pair or "ot a 'eis base (1) 2

(c) (i)

G " 3 " , e ? $ C l $ C l o r $ 3 0 a C l ? $ c lo r o r ( 1 )

" o t h i " # " o t h i " # h i t e p p t ( 1 )

c o l o u r c o l o u r " o t h i " # ( 1 ) s e e " s e e "

o r $ . 3

2 24

(ii)

+

+

2

2 2 7

233 34 . a $ . $ . a C < 5 " ? $ . a C o r o r ( 1 )

# r e e " p p t d e c o l o u r i s e d " o f i H H ( 1 )

b r o " p p t " o t h i " # " o f i H H ( 1 )

( # r e e " )

( < C r ? $ )

alter"aties–

c o " c $ C l < ;" o t h i " # " o t h i " #y e l l o ) r e d ? b r o ) "

6[13]

20. (i) #ree"–blue or pi" ppt (1)

%Co($)2($2)4& or Co($)2 (1)

(ii) #oes bro" (1)

%Co($)3($2)3& or Co($)3 (1)

or Co($)

4[1-]

21. (a) (i) Co"c or !s .$3 (1) air or 2 or $22 (1)

(ii) Co"c (1) $Cl (1)

(iii) .a$ (1) $22 (1)

(i) G" (1) $Cl or dil $24 F

(b) @issole i" dil $Cl or dil $24 (1)

add !s (1) .a2C3 (1)

filter off ppt (1)

or ,eC3 precipitates

Acid ust be prese"t to score last 3 ars 4[1"]

22. ,orula of 8 %C($2)6&2+

(1)

hape of 8 octahedral (1)

,orula of %CoCl4&2–

(1)

hape of tetrahedral (1)



uatio" %Co($2)6&2+

+ 4Cl –

%CoCl4&2–

+ 6$2 (1)

*[0]

23. (a) (i) 8ormua of ,reci,itate %Co($)2($2)4& or Co($)2 (1)

41uations

%Co($2)6&2+

+ 2.$3 → %Co($)2($2)4& + 2.$+

4 (2)

or %Co($2)6&2+

+ 2$ –

(2$2) → %Co($)2($2)4& + 2$2 (2$3+) (1)

$2 ($3+) + .$3 → .$

+

4 + $ –

($2) (1)

(ii) %Co(.$3)6&2+

(1)

%Co($)2($2)4& + 6.$3 → %Co(.$3)6&2+

+ 4$2 + 2$ –

(2)

(iii) dar"ess or #oes bro" (1)

%Co(.$3)6&3+

(1) F

[8]

24. (a) (i) ' electro" pair do"or (1)

:A electro" do"or (1)

(ii) A"y r" i" hich r –

do"ates lo"e pair (1)

e/#/ %Co($2)6&2+

+ 4r –

→ Cor – 24 + 6$2

$+ + r

– → $r9 C$

+

3 + r –

→ C$3r9 Alr 3 + r –

→ Alr –

4

A"y r" i" hich r –

acts as :A (1)

e/#/ 2r – + Cl2 → r 2 + 2Cl – 9 2$r + $24 → r 2 + 2 + 2$2 4

(b) ,e4?2?$22?,e?stated aldehyde 1y or 2

y :$ (1)

acid or dil $24 (aboe) (1)

Cr 2 – 27 + 14$

+ + 6,e

2+ → 2Cr

3+ + 7$2 + 6,e

3+ (2)

or to half-euatio"s

G" (1) $Cl or dil $24 (1)

abse"ce of air (1)

Cr 2 – 27 + 14$

+ + 4G" → 2Cr

2+ + 7$2 + 4G"

2+ (2)

or to half-euatio"s B(c) #ree" ppt (1) efferesce"ce (1)

%Cr($)3($2)3& or Cr($)3 (1)

ppt (1)

CrC3 (1) *

[18]



25. (a) $i%and& '

atom ion or molecules ic can donate a #air of electrons to a metal ion* "

co-ordi"ate bo"d-

a coale"t bo"d 1

i" hich both electro"s are do"ate by o"e ato 1

(b) (i) To correct cople! io"s 1

ala"ced euatio" 1

To correct colours 2

(ii) Cople! ith a bide"tate li#a"d 1

ala"ced euatio" 1

/B e" not aowed as a igand uness structure aso given

5ore olecules?io"s fored 1

;"crease i" e"tropy 1

ore stable cople! fored 1

5a! 2

(c) ∆

49 e"er#y absorbed by electro" #rou"d to e!cited state (I o ') 1h9 8la"cJs co"sta"t or a co"sta"t 1

Cha"#e i"

!idatio" state 1

'i#a"d 1

Co-ordi"atio" "uber 1

0,,y ist ,rinci,e to incorrect additiona answers

[1]

26. (a) replacee"t of 1 li#a"d by a"other (1)

Cu4

b l u e p p t (1) deep blue (blue iolet) solutio" (1)

%Cu($2)6&2+

+ 2.$3 → %Cu($)2($2)4& + 2.$4+ (1)

or .$3 + $2 → .$4+ + $

– K

%Cu($2)6&2+

+ 2$ –

→ %Cu($)2($2)4& + 2$2 K

%Cu($)2($2)4& + 4.$3 → %Cu(.$3)4($2)2&2+

+ 2$ –

forula (1) + 2$2 (1)

Cr 2(4)3

# r e e " p p t (#rey–#ree") (1) purple (lilac aue) solutio" (1)

%Cr($2)6&3+

+ 3.$3 → %Cr($)3($2)3& + 3.$4+ (1)

or .$3 + $2 → .$4+ + $

– K

%Cr($2)6&3+

+ 3$ –

→ %Cr($)3($2)3& + 3$2K

%Cr($)3($2)3& + 6.$3 → %Cr(.$3)6&3+

+ 3$ –

+ 3$2

forula (1) (1)

11



(b) (i)

% C u ( . $ C $ C $ . $ ) ( $ ) & 2 +

( 1 )( 1 )

( o r L e " L )2 2 2 2 2 2 2

(ii)

3 +

( 1 )( 1 )

2 2 2 2 3% C o ( . $ C $ C $ . $ ) &

4

[10]

27. A Cur 2 (1)

%Cu($2)6&2+

(1)

C r –

(1)

@ %Cu($)2($2)4& or Cu($)2 (1)

%Cu(.$3)4($2)2&2+

(1)

, %CuCl4&2–

(1)

> A#r (1)

$ %A#(.$3)2&+ (1)

; A#(23)2&3–

(1) B

Cur 2 + 6$2 → %Cu($2)6&2+

+ 2r –

(1)

%Cu($2)6&2+

+ 2.$3 → %Cu($)2($2)4& + 2.$+

4 (1)

(or 2 euatio"s for" $

– use of $

– )

%Cu($)2($2)4& + 4.$3 → %Cu(.$3)4($2)2&2+

+ 2$ –

+ 2$2 (1)

%Cu($2)6&

2+

+ 4Cl

–

(4$Cl)→

%CuCl4&

2–

+ 6$2 (+4$

+

) (1)

A#+ + r

– → A#r or A#.3 + r

– → A#r + .

–

3 (M) (1)

A#r + 2.$3 → %A#(.$3)2&+ + r

– (M) (1)

A#r + 22 – 23 → %A#(23)2&

3– + r

– (M) (1)

(M) allo A#Cl here if C #ie" as Cl –

a! 6[10]



28. (a) H2O or OH bro,en (1) H+ formed (1)

[-(H2O)6]2+

+ H2O → [-(H2O).(OH)]+ + H3O

+ (1)

a"y etal a"y base

proto"ated base

%5($2)6&3+

+ $2 → %5($2)*($)&2+

+ $3+ (1)

53+

ore acidic tha" 52+

(1) hi#her char#e?siHe rated (1) or char#e de"sity

53+

polarises $2 ore (1) –$ bo"d eae"ed (1)

52+

→ 5C3 (1) 53+ → %5($)3($2)3& (1)

52+

eaer acid tha" $2C3 or "ot e"ou#h $3+ to react ith C

– 23 (1)

53+

stro"#er tha" or displaces $2C3 or ore $3+ so ca" react ith C

– 23 (1)

or e" shoi"# C

– 23 → C2 12

(b) #ree" ppt is %Cu($2)*($)&+ or %Cu($2)*($)&24 (1)

%Cu($2)6&2+ + $2 (or $ – ) → %Cu($2)*($)&+ + $3+ ($2) (1)

$ –

reoes $3+ or pushes e

" to :$ (1)

blue ppt is %Cu($2)4($)2& (1)

%Cu($2)6&2+

+ 2$2 ($ –

) → %Cu($2)4($)2& + 2$3+ ($2) (1)

or %Cu($2)*($)&+ + $2 ($

– ) → %Cu($2)4($)2& + $3

+ ($2)

$ –

reoes $3+ or pushes e

" to :$ (1)

blue solutio" is %Cu($)4&2–

or %Cu($)4($2)2&2–

or %Cu($)3($2)3& –

(1)

%Cu($2)4($)2& + 2$ –

→ %Cu($)4&2–

(or other) + 4$2 (1)

substitutio" or aphoteris or ust be a" io" (1) 5a! F["-]

transition metal complex marksheme

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