MEMORANDUM

QUESTION 1
1.1 C (2)
1.2 C (2)
1.3 D (2)
1.4 C (2)
1.5 D (2)       [10]

QUESTION 2
2.1 Functional group (1)
2.2 Macromolecule (1)
2.3 Semiconductor (1)
2.4 Electrolysis (1)           [4]

QUESTION 3
3.1 Doping is the process of adding impurities to an intrinsic semiconductor to improve its conductivity.  (2)
3.2

• Silicon is a pure semiconductor, as impure atoms must be added to improve conductivity.
  OR
• A pure semiconductor which is undoped.(2)

3.3 3.3.1 P-type semiconductor/P-tipe halfgeleier (1)
3.3.2 A diode allows the current to flow in one direction only.  (1)
[6]

QUESTION 4
4.1 4.1.1 C OR G (1)
4.1.2 A (1)
4.1.3 A AND E (2)
4.1.4 B (1)
4.1.5 E (1)
4.2
 (2)
4.3 4.3.1 Addition(1)
4.3.2 HBr (1)
4.4 Pentanoic Acid and Ethanol (2)
[12]

QUESTION 5
5.1 A series of organic molecules that is defined by the same general formula and where each member differs from the next by a CH₂ group. (2)
5.2

• An increase in the number of branched chains results in a decrease in the boiling point.
  OR
• Straight chain alkanes have a higher boiling point compared to their corresponding branched chains. (1)

5.3 

• Straight-chained molecules can get closer to one another than branched molecules and have larger surface area in contact for intermolecular forces to form, therefore the Van der Waals forces/london forces are stronger. hence more energy is required to overcome intermolecular forces between the straight chain molecules compared to branched chains. therefore, straight-chained molecules have a higher boiling point.
  OR
• Branched chains form molecules that are more spherical with fewer points of contact for intermolecular forces. Therefore, the Van der Waals forces / London forces are weaker. Hence less energy is required to overcome intermolecular forces between the branched chains compared to straight chains, thus a lower boiling point. (4)

5.4 The learner should:

• Avoid direct heating with an open flame.
• Work in a well-ventilated area. Any one
• Use a fume hood.
  Reason: Alkanes are fuels and are highly flammable  (2)

[9]

QUESTION 6
6.1

(4)

MARKING CRITERIA 

• Correct structure of reactants. (2)
• Correct structure of the product(2)

6.2 Hydrohalogenation/addition. (1)
6.3

Butan-2-ol (2-butanol) (3)
6.4 Hydrolysis (1)
6.5
6.5.1 Water (1)
6.5.2 H₂SO₄ / HCℓ / H₃PO₄ (1)
6.5.3 Hydration (Accept: Addition) (1)
6.6

• Manufacturing of plastic bags (Any one )
• Synthesis of bullet proof vests
• Manufacturing of squeeze bottles
• Manufacturing of cling wrap (1)

[13]

QUESTION 7
7.1

• An electrolyte is a substance of which the aqueous solution contains ions.
  OR
• A substance that dissolves in water to give a solution that conducts electricity.
  OR
• A substance that forms free ions when melted.  (2)

7.2 Electrolytic cell (1)
7.3

7.3.Cu²⁺ (aq) + 2e– → Cu (s) (1)
7.3.2 2Cl^- (aq) → Cl₂(g) + 2e^- (1)
7.4 Chlorine (1)
7.5 Conversion of electrical energy to chemical energy. (1)
[7]

QUESTION 8
8.1

• Salt bridge. It maintains electrical neutrality.
  OR
• It separates the two compartments so that they do not mix.  (2)

8.2 Chemical energy is converted into electrical energy.  (1)
8.3 It is a non-spontaneous reaction. (1)
8.4
8.4.1

• Eᶿcell = Eᶿcathode - EᶿAnode
  = -0,74 – (-0,76)
  = 0,02 V
  OR
• Cr³⁺ +3e^- → Cr         E^θ= -0,74
  Zn →Zn²⁺ +2e^-         E^θ = +0,76
                                   E^θ_cell = 0,02 V                (3)

8.4.2 Decreases (1)
8.5 Measurements are not done under standard conditions of temperature at 25 °C and concentration of electrolytes of 1 mol·dm^-3. (2)
8.6
8.6.1 Fuel cell/Brandstofsel (2)
8.6.2 It increases energy security, improves the quality of air and the environment. (ANY ONE )  (1)
8.6.3 More expensive than petroleum.

• Not suitable for use in low temperatures. (Any one)
• Could harm rubber hoses of some engines.
• Can contribute to food shortage. (1)

[14]
TOTAL: 75