CADANGAN JAWAPAN PSPM 20202021

CADANGAN JAWAPAN PSPM 2020/2021
CHEMISTRY 2 (SK 025)

SOALAN 1

a) i. Order of reaction
1st t 1/2= 125 s (range 125-130s)
2nd t 1/2= 250 s (range 250-265s)

Since 2 1/2 = 2, thus this is a second order reaction.
1 1/2

Rate equation,

Rate = k[HI]2

ii. rate constant
1

1/2 = [ ]0

1
130 = [0.1]

k = 0.0769 M-1s-1

rate= k[HI]2

= 0.0769 (0.1)2

= 7.69 X 10-4 Ms-1

b) 2 requirements for effective collision:
- Molecules collide with correct orientation.
- Molecules possess kinetic energy equal or greater than activation energy (Ea).

(*used molecules not particles or reactant)

SOALAN 2

a) i. ΔHo lattice energy = -915 kJ AgCl(s)

Ag+ (g) + Cl-(g)

= -465 kJ = -364 kJ

ΔHo solution

Ag+ (aq) + Cl- (aq)

ii. ∆Ho lattice energy = ∆Ho hyd Ag+ + ∆Ho hyd Cl- - ∆Ho solution

-915 kJmol-1 = -465 kJmol-1 + (-364 kJmol-1) - ∆Ho solution

∆Ho solution = +86 kJmol-1

b) NaCl< MgCl2< AlCl3
- The charge of cations increases from Na+ to Mg2+ to Al3+.
- The ionic radius of the cation decreases from Na+ to Mg2+ to Al3+.
- The higher the charge of the cations, the stronger the attraction toward Cl- ion.
- Thus, the lattice energy increase NaCl< MgCl2< AlCl3

SOALAN 3

a) Overall equation:

anode: Pb(s) Pb2+ (aq) + 2e

cathode: 2VO2+ (aq) + 4H+ (aq) + 2e 2VO2+ (aq) + 2H2O (l)
Pb2+ (aq) + 2VO2+ (aq) + 2H2O (l)
overall : Pb(s) + 2VO2+ (aq) + 4H+(aq)

b) Standard cell potential:
Eo cell= Eo cathode - Eo anode
= + 1.0V – (-0.13V)
= + 1.13 V

c) = − 0.0592 log [ 2+][ 2+]2
2 [ 2+ ]2[ +]4

0.0592 (0.25)(0.1)2
= +1.13 − 2 log (0.1)2(0.05)4

= + 0.994 V

SOALAN 4
a)
C6H12 hydrocarbons: alkenes or cycloalkanes (*possible isomeric form)

A decolourised bromine water : A is an alkenes/contain carbon-carbon double bond/
unsaturated hydrocarbon.

C formed single product from ozonolysis: C is a symmetrical alkene.

C forms brick red precipitate when treated with CuSO4.Positive Fehling’s test: C is an
aldehyde.

A : CH3CH2CH=CHCH2CH3
B:

SOALAN 5

a) Electrophilic aromatic substitution
b) E : Br2, uv (cannot used Cl2 because Cl2 will form a mixture)

F : KOH, ethanol reflux
c) H:

Br
C CH3
H

d) Mechanism:

Br Br + FeBr3 +

Br FeBr3-

H3CH2C H3CH2C H3CH2C
H+
+ Br FeBr3- H
Br Br
H
+

H3CH2C +

H

Br

H3CH2C + H3CH2C

H + + HBr + FeBr3

+ Br FeBr3- Br

Br

SOALAN 6 A B
a) i.
H3C C CH CH3 H2C C CH2 CH3
i) CH3 CH3

ii. major product : A

b) Mechanism H3C CH3 + Br-
C+ CH2 CH3
CH3
H3C C CH2 CH3

Br

H3C CH3 + H2O CH3
C+ CH2 CH3 H3C C CH2 CH3

CH3 + H2O H O+
H
H3C C CH2 CH3
H O+ CH3
H
H3C C CH2 CH3 + H3O+

OH

SOALAN 7

a) Oxidation K produce carboxylic acid. K is a 10 alcohol.
L resists oxidation. L is a 3o alcohol.

Structure K : CH3CH(CH3)CH2OH

Structure L : CH3C(CH3)OHCH3

b) H3C KMnO4, H+ H3C
H3C CH CH2 Δ
OH H3C CH C OH + Mn02

O

SOALAN 8

a) M positive iodoform test/ react with I2 in NaOH(aq). M is methyl carbonyl.
N rotate plane polarized light. N contain chiral carbon/N contain C bonded to 4 different
atoms of groups of atoms.
N form silver mirror/positive Tollens’ test. N is an aldehyde.

O O
CH2 C CH3 CH C H
CH3
M
N

b) O O
CH2 C
CH2 C CH3 I2, NaOH O-Na+ + CHI3

O I2, NaOH O O-Na+ + CHI3

CH C H CH C
CH3 CH3

SOALAN 9

a) P vinegar smell. P is a carboxylic acid.
Q sweet smell. Q is an ester.

O O
H3C CH2 C OH H C O CH2CH3

P Q

*Q only this structure because stated in the question hydrolysis of Q produced a compound with reducing
properties. Methanoic acid has the reducing properties)

b)

O PCl5 O
H3C CH2 C OH H3C CH2 C Cl
+ HCl

(HCl compulsory to write because stated in the
question the reaction produce a white fume)

c)

Mg, dry ether CH3CH2MgBr i. CO2 CH3CH2COOH
ii. H3O+
CH3CH2Br

@

KCN CH3CH2CN H3O+ CH3CH2COOH

CH3CH2Br

SOALAN 10

a) Primary amine: CH3CH2CH2CH2NH2
Secondary amine: CH3CH2CH2NH(CH3)
Tertiary amine : CH3CH2N(CH3)2

(* or any correct structure)

b) Boiling point :
Tertiary amine < secondary amine < primary amine ( refer to structure given)

-1o amine higher than 2o and 3o because it can form more hydrogen bonds.
-3o amine has no hydrogen bond/ only has weak van dar Waals forces.
-Hydrogen bond is stronger than van dar Waals forces.

SOALAN 11 HO
H2N C C OH
CH3O
H3C C C OH CH2
OH
NH2
T (Mesti dalam list alpha amino acid)
S
HH O
CH3O
NC C OH
R H3C C C
CH2
NH2

OH

Peptide bond

SOALAN 12
a) Addition polymer @ homopolymer
b) Monomer : CF2=CF2

Prepared by:
Marziah binti Mohamad
Chemistry Lecturer, Kolej Matrikulasi Melaka