SOLUCIONARIO QUÍMICA ORGÁNICA
1.
PRUEBA 09/11
C
[1]
2.
B
[1]
3.
C
[1]
4.
B
[1]
5.
(a) boiling points increase (from the first member to the fifth member);
increasing size of molecule/area of contact/number of electrons (from
the first to the fifth member);
strength of intermolecular/van der Waals’/London/dispersion forces
increase / more energy required to break the intermolecular bonds
(from first member to fifth member);
(b)
same general formula;
successive members differ by CH2;
same functional group / similar/same chemical properties;
gradual change in physical properties;
Accept specific physical property such as melting point, boiling
point only once.
3
2 max
[5]
6.
A:
B:
C:
IB Questionbank Chemistry
1
1,2-dichloroethane;
D:
Accept condensed formulas.
Penalize missing hydrogens only once.
5
[5]
7.
add bromine water/bromine;
pentane no change/stays brown and pent-1-ene decolourizes bromine
water/bromine;
OR
add acidified KMnO4;
pentane no change/stays purple and pent-1-ene decolourizes acidified KMnO4;
Accept any correct colour change.
Do not accept “clear” instead of “colourless”.
2 max
[2]
8.
E: primary and F: secondary;
G: primary;
G / E: only one alkyl group/2 H atoms attached to the carbon atom
attached to the Cl / only one carbon atom attached to the carbon atom
attached to the Cl;
F: two alkyl groups/1 H atom attached to the carbon atom attached to
the Cl / two carbon atoms attached to the carbon atom attached to the Cl;
4
[4]
9.
Initiation:
UV/hf / hv / heat
→ 2Cl•;
Cl2    
Reference to UV/hf/hν/heat must be included.
Propagation:
Cl• + CH4 → CH3• + HCl;
CH3• + Cl2 → CH3Cl + Cl•;
Termination:
Cl• + Cl• → Cl2 / CH3• + Cl• → CH3Cl / CH3• + CH3• → C2H6;
Allow representation of radical without • (e.g. Cl, CH3) if consistent
throughout mechanism.
If representation of radical (i.e. •) is inconsistent, penalize once only.
4
[4]
10.
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2
Accept condensed formulas.
Award [1 max] if A and D are other way round (and nothing else correct).
Award [2 max] if A and D are other way round but one substitution product
B or E is correct based on initial choice of A and D.
Award [3 max] if A and D are other way round but both substitution
products B and E are correct based on initial choice of A and D.
M2 (for B) and M5 (for E) may also be scored for substitution product
if primary chloroalkane used.
Penalize missing hydrogens once only.
5
[5]
11.
B
[1]
12.
D
[1]
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3
13.
D
[1]
14.
C
[1]
15. (i)
addition of bromine/bromine water;
the bromine colour remains with propane and propene
decolourizes the bromine / solution changes from brown to colourless;
Do not accept “clear” instead of “colourless”.
(ii)
addition (polymerization);
( CH(CH3)–CH2 ) / –CH(CH3)CH2–;
Continuation bonds necessary for mark, displayed formula or
condensed structural formula can be given.
Accept if more than one repeating unit is shown.
(iii)
hydrogenation (of vegetable oils) / manufacture of margarine /
manufacture of ethanol / addition of water;
Accept manufacture of alcohol.
Do not accept hydrogenation of alkenes.
2
2
1
[6]
1
O2 → 3CO2 + 4H2O / 2C3H8O + 9O2 → 6CO2 + 8H2O
2
Award [1] for correct products and reactants and [1] for correct
balancing.
Ignore state symbols.
16.
(i)
C3H8O + 4
(ii)
acidic solution / H+ / sulfuric acid;
warm / heat / reflux;
(the solution changes) from orange to green;
2
3
(iii)
CH3CH2CHO and propanal;
CH3CH2COOH and propanoic acid;
CH3COCH3 and propanone/acetone;
Award [1] for 2 or 3 correct names or structures, award [2] for
4 or 5 correct names or structures.
propan-1-ol gives propanal and propanoic acid and propan-2-ol
gives propanone;
propan-1-ol has two H atoms bonded to the C containing the
–OH whereas propan-2-ol only has one / propan-1-ol is a primary
alcohol and propan-2-ol is a secondary alcohol;
5
[10]
17.
B
[1]
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4
18.
D
[1]
19.
B
[1]
20.
B
[1]
21.
A
[1]
22.
(i)
Accept lines, dots or crosses for electron pairs.
Lone pairs required on chlorine.
(approximately)120°;
Accept any bond angle in the range 113–120°.
2
(ii)
Brackets not required for mark.
Allow correct condensed structural formula.
Continuation bonds from each carbon are required.
Cl atoms can be above or below carbon spine or alternating
above and below.
1
(iii)
plastics are cheap/versatile/a large industry / plastics have
many uses / OWTTE;
plastics are not biodegradeable / plastics take up large amounts of space in
landfill / pollution caused by burning of plastics / OWTTE;
Do not accept plastics cause litter.
Allow plastics don’t decompose quickly / OWTTE.
2
[5]
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5
23. (i)
Step 1:
CH2CHCl + H2 → CH3CH2Cl;
Step 2:
CH3CH2Cl + OH– → CH3CH2OH + Cl–;
Allow NaOH or NaCl etc. instead of OH– and Cl–.
Allow abbreviated formulas C2H3Cl, C2H5Cl, C2H5OH.
2
(ii)
H2SO4/H+/acidified and Cr2O72–/(potassium/sodium) dichromate;
Accept suitable oxidizing agents (e.g. KMnO4 etc.) but only with acid.
Ignore missing or incorrect oxidation states in reagents.
(heat under) reflux;
Second mark can be scored even if reagent is incorrect.
(iii)
CH3COOH(aq) + H2O(l)
2
CH3COO–(aq) + H3O+(aq)
OR
CH3COOH(l) + H2O(l)
CH3COO–(aq) + H3O+ (aq)
OR
CH3COOH(aq)
CH3COO–(aq) + H+(aq)
correct equation;
state symbols and
;
BL acid is CH3COOH and cb is CH3COO– / BL acid is H3O+ and cb is H2O;
3
[7]
24. same general formula;
same functional group;
successive members differ by CH2;
Allow methylene for CH2.
similar chemical properties;
gradually changing physical properties;
2 max
[2]
25. (a) (i)
A: butan-1-ol;
B: butan-2-ol;
C: (2-)methylpropan-2-ol;
D: (2-)methylpropan-1-ol;
Accept answers in the form of 1-butanol and 2-methyl-2-propanol etc.
Penalize incorrect punctuation, e.g. commas for hyphens, only once.
4
(ii)
C/(2-)methylpropan-2-ol;
1
(iii)
A/butan-1-ol;
1
(iv)
B/butan-2-ol;
1
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(v)
1
(b)
(i)
SN2;
1
(ii)
curly arrow going from lone pair/negative charge on O in OH– to C;
Do not allow curly arrow originating on H in OH–.
curly arrow showing Br leaving;
Accept curly arrow either going from bond between C and Br to Br in
1-bromobutane or in the transition state.
representation of transition state showing negative charge, square
brackets and partial bonds;
Do not penalize if HO and Br are not at 180° to each other.
Do not award third mark if OH----C bond is represented.
3
[12]
26.
B
[1]
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27.
A
[1]
28.
B
[1]
29. (i)
colour change from yellow/orange/rust colour/red/brown to colourless;
No mark for change to clear, or for decolourized with no reference
to original colour.
(ii)
1
Chloroethene:
No mark if the lone pairs missing on Cl.
Accept lines, dots or crosses for e– pairs.
Poly(chloroethene):
;
n and square brackets are not required.
Continuation bonds must be shown.
2
(iii)
(hydration of ethene for the manufacture of) ethanol/ C2H4 + H2O → C2H5OH;
(synthesis of) CH3COOH /ethanoic/acetic acid;
(synthesis of) ethylene glycol/1,2-ethanediol/ethane-1,2-diol;
(synthesis of) drugs/pesticides;
(hydrogenation of unsaturated oils in the manufacture of) margarine;
Accept other commercial applications.
2 max
[5]
30.
(i)
Penalize missing H atoms once only.
2
(ii)
CH3CH=CHCH3 + H2O → CH3CH(OH)CH2CH3;
concentrated sulphuric acid/ H2SO4 and heat/steam / phosphoric acid/H3PO4
IB Questionbank Chemistry
8
(catalyst) and heat/steam;
3CH3CH(OH)CH2CH3 + Cr2O72– + 8H+ → 3CH3COCH2CH3 + 2Cr3+ + 7H2O;
Accept CH3CH(OH)CH2CH3 + [O] → CH3COCH2CH3 + H2O .
Accept C2H5 as CH2CH3.
dichromate(VI) (ion)/Cr2O72– and acidic/H+;
Accept MnO4– in place of Cr2O72– in third and fourth marks.
heat/reflux;
5
[7]
31. (i)
CH3CH2CH2OH, propan-1-ol/1-propanol;
CH3CH(OH)CH , propan-2-ol/2-propanol;
Need both formula and name for mark.
Accept either condensed or full structural formulas.
CH3CH2CH2OH: primary and CH3CH(OH)CH3: secondary;
3
(ii)
CH3CH2CHO;
CH3CH2COOH;
CH3COCH3;
Accept either condensed or full structural formulas.
from propan-1-ol: CH3CH2CHO(propanal) obtained by distillation (as
product is formed);
propan-1-ol gives CH3CH2COOH (propanoic acid) by (heating under) reflux;
Award [1] if CH3CH2CHO and CH3CH2COOH identified but conditions
not given/incorrect.
propan-2-ol gives CH3COCH3 by heat / reflux;
5 max
[8]
32.
A
[1]
33.
B
[1]
34.
A
[1]
35.
C
[1]
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9
36.
B
[1]
37. (a) methylpropene;
Accept 2-methylpropene.
1
(b)
1
(i)
brown/orange/yellow to colourless / bromine is decolorized;
(ii)
1,2-dibromo-2-methylpropane / 1,2-dibromomethylpropane / 1-bromo-2methylpropan-2-ol / 1-bromomethylpropan-2-ol;
Do not penalize missing commas, hyphens or added spaces.
Award [1] if structure and correct name are given for 2-bromo-2methylpropan-1-ol.
2
[4]
38. (i)
synthesis of materials not naturally available/plastics;
chemically unreactive materials produced;
wide range of uses/physical properties / versatile;
cheap;
large industry;
uses a limited natural resource;
Award [2] for any two.
(ii)
addition;
2 max
1
(iii)
Must show continuation bonds.
Ignore bracket around the 6 carbons.
Must have 6 carbons joined to each other along chain.
1
(iv)
monomers are smaller molecules / have smaller surface area than polymers;
Accept monomers have lower molecular mass.
with weaker intermolecular/Van der Waals’/London/dispersion forces;
Accept opposite argument for polymers.
2
[6]
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39. chloroethane;
(electrophilic) addition;
Do not accept free radical/nucleophilic addition.
2
[2]
81.7
18.3
= 6.80 and nH =
= 18.1;
12.01
1.01
ratio of 1: 2.67 /1: 2.7;
C3H8;
No penalty for using 12 and 1.
40.
(a)
nC =
3
C3H8;
1
(c)
(i)
Br2 /bromine;
UV/ultraviolet light;
Accept hf/hv/sunlight.
2
(b)
(ii)
Accept names.
Cr2O72– /MnO4– and acidified/ H+ /H3O+;
heat / reflux;
2
(d)
Initiation:
Br2 → 2Br•;
Propagation:
Br• + RCH3 → HBr + RCH2•;
RCH2• + Br2 → RCH2Br + Br•;
Termination: [1 max]
Br• + Br• → Br2;
RCH2• + Br• → RCH2Br;
RCH2• + RCH2• → RCH2CH2R;
Award [1] for any termination step.
Accept radical with or without • throughout.
Do not penalize the use of an incorrect alkane in the mechanism.
(e)
(i)
substitution and nucleophilic and bimolecular/two species in
rate-determining step;
Allow second order in place of bimolecular.
IB Questionbank Chemistry
4 max
1
11
(ii)
curly arrow going from lone pair/negative charge on O in OH– to C;
Do not allow curly arrow originating on H in OH–
curly arrow showing Br leaving;
Accept curly arrow either going from bond between C and Br to Br in
bromoethane or in the transition state.
representation of transition state showing negative charge, square
brackets and partial bonds;
Do not penalize if HO and Br are not at 180° to each other.
Do not award M3 if OH ---- C bond is represented unless already
penalized in M1.
Do not penalize the use of an incorrect alkyl chain in the mechanism.
3
[16]
41. (i)
CH3OCH2CH;
CH3CHOHCH;
Allow more detailed structural formulas.
(ii)
CH3CHOHCH3 has higher boiling point due to hydrogen bonding;
CH3OCH2CH3 has lower boiling point due to Van der Waals’/London/
dispersion/dipole-dipole forces;
hydrogen bonds in CH3CHOHCH are stronger;
Allow ecf if wrong structures suggested.
2
2 max
[4]
42.
A
[1]
43.
C
[1]
44.
C
[1]
45.
A
[1]
46.
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47.
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48.
D
[1]
49.
C
[1]
50.
A
[1]
51.
C
52. (i)
energy required to break (1 mol of) a bond in a gaseous molecule/state;
Accept energy released when (1 mol of) a bond is formed in a gaseous
molecule/state / enthalpy change when (1 mol of) bonds are made or
broken in the gaseous molecule/state.
average values obtained from a number of similar bonds/
compounds / OWTTE;
2
(ii)
Bonds broken
(1)(C–C) + (1)(O–H) + (5)(C–H) + (1)(C–O) + (3)(O=O)
= (1)(347) + (1)(464) + (5)(413) + (1)(358) + (3)(498) = 4728(kJ);
Bonds formed
(2 × 2)(C=O) + (3 × 2)(O–H)
= (4)(746) + (6)(464) = 5768 (kJ);
∆H = 4728 – 5768 = –1040 kJ mol–1 / –1040 kJ;
Units needed for last mark.
Award [3] for final correct answer.
Award [2] for +1040 kJ.
3
(iii)
Mr(C2H5OH) = 46.08 / 46.1 and Mr(C8H18) = 114.26/114.3;
1 g ethanol produces 22.57 kJ and 1 g octane produces 47.88 kJ;
Accept values ranges of 22.5–23 and 47.8–48 kJ respectively.
No penalty for use of Mr = 46 and Mr = 114.
2
(iv)
A: CH3CHO;
B: CH3COOH/CH3CO2H;
Accept either full or condensed structural formulas but not the
names or molecular formulas.
B: reflux;
A: distillation;
4
(v)
ethanol/CH3CH2OH;
hydrogen bonding (in ethanol);
Award second point only if the first is obtained.
2
(vi)
(concentrated) H3PO4 /(concentrated) phosphoric acid / H2SO4/sulfuric acid;
dyes / drugs / cosmetics / solvent / (used to make) esters / (used in) esterification/disinfectant; 2
[16]
IB Questionbank Chemistry
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53.
(i)
(2-)methylbutane / (2,2-)dimethylpropane;
1
(ii)
curly arrow going from O/lone pair of OH–(but not H) to the C attached to Br;
leaving of Br;
transition state representation with both Br and OH attached to C–1;
correct products CH3(CH2)4OH and Br–;
Charge must be shown for TS.
C–OH and C–Br bonds in TS must be represented by dashed lines.
4
[5]
54.
B
[1]
55. A: CH3CHO;
B: CH3COOH/CH3CO2H;
Accept either full or condensed structural formulas but not the names
or molecular formulas.
A: distillation;
B: reflux;
4
[4]
56. (concentrated) H2PO4/(concentrated) phosphoric acid / H2SO4/sulfuric acid;
dyes / drugs / cosmetics / solvent / (used to make) esters / (used in)
esterification / disinfectant;
2
[2]
57.
C
[1]
58.
A
[1]
59.
D
[1]
IB Questionbank Chemistry
15
60.
C
[1]
61.
(a)
(i)
Isomer
Boiling point
A
B
C
36 °C
28 °C
10 °C
Award [1] if correct boiling points are assigned to 3 isomers.
increase in branching / more side chains / more spherical shape /
reduced surface contact / less closely packed;
weaker intermolecular force/van der Waals’/London/dispersion forces;
Accept the opposite arguments
3
(ii)
B: 2-methylbutane/methylbutane;
C: 2,2-dimethyl propane/dimethyl propane;
Do not penalize missing commas, hyphens or added spaces.
Do not accept 2-dimethylpropane, or 2,2-methylpropane.
(b)
C5H12;
Accept any two of the following explanations.
C5H11OH has greater molar mass / produces less grams of CO2 and
H2O per gram of the compound / suitable calculations to show this;
C5H11OH contains an O atom which contributes nothing to the energy
released / partially oxidized / OWTTE;
analogous compounds such as butane and butan-1-ol show a lower
value for the alcohol per mole in the data book / OWTTE;
the total bond strength in the pentanol molecule is higher than the total
bond strength in pentane;
the total amount of energy produced in bond formation of the products
per mole is the same;
fewer moles of pentanol in 1 g;
pentanol requires more energy to break intermolecular forces/
hydrogen bonding / OWTTE;
3 max
[8]
62.
(i)
C4H9Cl + KOH → C4H9OH + KCl;
(ii)
(substitution)
nucleophilic;
unimolecular / OWTTE;
1
2
(iii)
1-chlorobutane:
SN2;
2-chloro-2-methylpropane:
SN1;
2
IB Questionbank Chemistry
16
(iv)
SN2 1-chlorobutane–allow ECF from (iii).
curly arrow going from lone pair or negative charge on O in OH– to C;
curly arrow for Cl leaving;
Can be shown in transition state.
formation of the transition state in bracket, with negative charge and dotted
lines to represent bonds;
SN1 2-chloro-2-methylpropane–allow ECF from (iii)
curly arrow showing Cl leaving;
formation of carbocation;
curly arrow from lone pair or negative charge on O in OH– to C+;
6
[11]
63.
(i)
Penalize missing H atoms once only.
IB Questionbank Chemistry
17
Accept correct condensed structural formulas.
4
(ii)
CH3–CH2–CH2–CHO / (CH3)2CHCHO;
CH3–CH2–CH2–COOH / (CH3)2CHCOOH;
2
(iii)
CH3–CH2–CO–CH3;
1
(iv)
orange to green;
1
(v)
1
[9]
64.
B
[1]
65.
C
[1]
66.
A
[1]
67.
B
68. A
69.
(a) one general formula / same general formula;
differ by CH2;
similar chemical properties;
gradual change in physical properties;
1
Award [1] for any two of the above characteristics.
(b)
ethanol lower / ethanoic acid higher;
due to larger mass of ethanoic acid/stronger van der Waals’/
London/dispersion forces;
due to stronger hydrogen bonding/2 hydrogen bonds per molecule;
2
Accept either answer for second mark.
IB Questionbank Chemistry
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(c)
2
Allow condensed structural formulas such as CH3CH2CH2CH2OH.
Award [2] for all three correct isomers, [1] for any two correct isomers.
[5]
70.
(i)
H
H
C
H
(Empirical formula =) C8H8O3;
H
O
O
C
H
O
;
H
H
H
2
Allow double bonds on arene in alternate positions, or allow delocalized representation
(of pi electrons).
(ii)
the bond at 0.1373 nm is a double bond and the bond at 0.1424 nm is a
single bond;
in CO2(g) both bonds are double bonds and would have a value
around 0.137 nm;
2
(iii)
Ester;
Arene/benzene ring;
Alcohol;
2
Award [2] for any three correct, award [1] for any two correct.
Do not accept alkane as a type of functional group in this molecule.
[6]
71. (i)
boiling point increases as the number of carbons increases / OWTTE;
Greater Mr and hence greater van der Waals’/London/dispersion
forces present;
(ii)
2
hv / UV light
→ CH3Cl + HCl;
CH4 + Cl2   
Do not award mark if hv/uv light is not given.
IB Questionbank Chemistry
19
Initiation step:
hv
/ UV
light

→
Cl2
2Cl•;
Do not award mark if hv/uv light is not given.
Penalize once only.
Propagation step:
CH4 + Cl• → CH3• + HCl;
CH3• + Cl2 → CH3Cl + Cl•;
Termination step:
Cl• + Cl• → Cl2 or Cl• + CH3• → CH3Cl or CH3• + CH3• → CH3CH3;
Allow fish-hook half-arrow representations i.e. use of
Penalize use of full curly arrows once only.
Penalize missing dots on radicals once only.
5
.
[7]
72. (i)
A. = CH3(CH2)7CHO;
B. = CH3(CH2)7COOH/CH3(CH2)7CO2H;
C. = (CH3)3COH;
D. = (CH3)2CO;
E. = BrCH2CH2Br;
5
Allow correct structural formulas.
(ii)
addition;
/-(CH2-CH2)3-/-(CH2)6-;
2
[7]
IB Questionbank Chemistry
20