MARKS: 75 

TIME: 1½ hours 

INSTRUCTIONS AND INFORMATION 

1. Write your FULL NAME and SURNAME in the appropriate spaces in the  ANSWER BOOK. 

2. This question paper consists of SIX questions. Answer ALL the questions.

3. Start each question on a NEW page in the ANSWER BOOK. 

4. Number the answers correctly according to the numbering system used in  this question paper. 

5. Leave ONE line between two sub-questions, for example between  QUESTION 2.1 and QUESTION 2.2. 

6. You may use a non-programmable calculator. 

7. You are advised to use the attached DATA SHEETS. 

8. Round off your FINAL numerical answers to a minimum of TWO decimal  places. 

9. You may use appropriate mathematical instruments. 

10. Show ALL formulae and substitutions in ALL calculations.

11. Give brief motivations, discussions et cetera where required.

12. Write neatly and legibly.

QUESTION 1: MULTIPLE-CHOICE QUESTIONS 

Various options are provided as possible answers to the following questions.  Choose the answer and write only the letter (A–D) next to the question numbers  (1.1 to 1.5) in the ANSWER BOOK, for example 1.6 E.  

1.1 The process of adding impurities to intrinsic semiconductors is called a(n) ...

A intrinsic semiconductor. 
B pure semiconductor. 
C doping. 
D purification. (2)

1.2 Consider the following structural formulae for compounds A and B. 

These compounds have the same … and differ with … 

A molecular formulae; positional isomers. 
B molecular formulae; position of the functional group. 
C molecules; positions. 
D position of the functional group; structural formulae. (2)

1.3 Study the organic reaction below and answer the following question.

CH₄ + Y → CO₂ + H₂O 

Which ONE of the following does Y represent, and which is the correct  reaction condition for products to form? 

A H₂O and excess water 
B O₂ and mild heat 
C H₂ and heat 
D O₂ and excess oxygen (2)

1.4 Which of the following sets is the correct for an N-type semiconductor? 

(2) 

1.5 P-n junction 

(i) In doping, a pure element is added to a semiconductor to improve the conductivity of the semiconductor. 

(ii) In doping, a catalyst is added to a semiconductor to improve the conductivity of the semiconductor. 

(iii) The n-region becomes positively charged because it has lost some  electrons. 

(iv) There is potential difference between the two sides of the diode.

(v) Electrons (few) gain enough thermal energy to cross the energy gap  (from the valence band) to the conduction band. 

Which ONE of the following combinations below is CORRECT for a p-n  junction? 

A (i) and (ii) 
B (ii) and (iii) 
C (i) and (iv) 
D (iii) and (iv) (2) [10]

QUESTION 2 (Start on a new page.) 

Consider the organic compounds represented by the letters A to H below and  answer the questions that follow. 

2.1 Define the term functional group. (2)

2.2 Write down the letter(s) that represents the following: 

2.2.1 A tertiary alcohol (1)

2.2.2 Unsaturated hydrocarbons (1)

2.2.3 An ester (1)

2.2.4 Hydrocarbons (1)

2.2.5 Positional isomers (1)

2.3 Write down the IUPAC name of the following: 

2.3.1 D (1)

2.3.2 B (1)

2.3.3 G (1)

2.4 Write down the: 

2.4.1 STRUCTURAL formula of compound F (2)

2.4.2 STRUCTURAL formula for the functional group of compound C (1)

2.4.3 MOLECULAR formula of compound A (1)

2.4.4 The name of the functional group of compound B (1) 

2.4.5 STRUCTURAL formula of compound E (2) [17]

QUESTION 3 (Start on a new page.) 

Students were observing the vapour pressure of three (3) organic compounds from  a homologous series with a general formula C_nH_2n+2, represented by X, Y and Z.  The number of carbon atoms of these organic compounds ranges between 3 carbon  atoms and 5 carbon atoms. Their results were graphed as follows: 

3.1 Define the term vapour pressure. (2) 

3.2 Use the table above to draw a sketch graph of vapour pressure versus molecular mass. (3) 

3.3 What hypothesis can be deduced from the graph? (1)

3.4 Give the industrial use of these organic compounds. (1) 

3.5 Explain the difference in the vapour pressure of compound Y and Z. Refer  to the MOLECULAR MASS, STRENGTH OF INTERMOLECULAR  FORCES and THE ENERGY NEEDED. (3) 

3.6 Which compound will have the …? (Write only X, Y or Z.) 

3.6.1 highest viscosity (1)

3.6.2 lowest melting point (1) 

3.6.3 highest boiling point (1) [13]

QUESTION 4 (Start on a new page.) 

The table below shows the boiling points of four organic compounds, represented  by the letters I to L, of comparable molecular mass. 

4.1 Define the term boiling point. (2)

4.2 In which homologous series does compound K in the table belong? (1)

4.3 Name the intermolecular forces in compound J. (1)

4.4 What trend can be observed from compound J to compound L, in the table? (1) 

4.5 An investigation was conducted on the boiling points of compounds I  and L. 

4.5.1 Provide the IUPAC name of compound L. (1) 

4.5.2 The comparison of I and L is a fair comparison. Give a reason  why this is a true statement. (1) 

4.5.3 Explain how the vapour pressure of compound I will compare to  that of compound L. (2) [9]

QUESTION 5 (Start on a new page.) 

Alcohol H can be converted to many other compounds and be a product of other  reactions. As such alcohol H was used to form an organic compound called propyl  butanoate. Study the table below and answer the questions that follow. 

5.1 Are the intermolecular forces in propyl butanoate WEAKER or STRONGER  than those in alcohol H? Write only WEAKER or STRONGER. (1) 

5.2 Identify alcohol H. (1)

5.3 Write down the type of reaction represented by the following reactions:

5.3.1 Reaction 1 (1)

5.3.2 Reaction 3 (1)

5.3.3 Reaction 5 (1)

5.4 For Reaction 2: 

5.4.1 Write down the STRUCTURAL FORMULA for the alkene. (2)

5.4.2 Is compound S, ORGANIC or INORGANIC? (1)

5.4.3 Explain the answer to QUESTION 5.4.2 above. (1)

5.5 For Reaction 1, write down: 

5.5.1 The balanced chemical equation using STRUCTURAL  FORMULAE (3) 

5.5.2 One reaction condition (1) 

5.6 For Reaction 5, write down: 

5.6.1 The STRUCTURAL FORMULA for alkane W (2)

5.6.2 NAME for compound Y (1) 

5.6.3 FORMULA for compound Z (1) [17]

QUESTION 6 (Start on a new page.) 

Study the diagram of a semiconductor below and answer questions that follow.

Note the following about semiconductors: 

• Some semiconductors are formed by adding impurities to them and some  formed at high temperatures where the atoms vibrate.  
• Semiconductors are used in the manufacture of electronic devices such as  diodes, transistors, and integrated circuits. 

6.1 Which element represents a dopant in the diagram? Write only Si or B. (1)

6.2 How many valence electrons does this dopant have? (1)

6.3 What does A in the diagram above, represent? (1)

6.4 Define a semiconductor. (2) 

6.5 Briefly explain what will happen if the semiconductor above is connected  across the terminals of a cell. (2) 

6.6 What is the purpose of doping? (1) 

6.7 Identify the type of a semiconductor represented by the diagram above. (1) [9] 

TOTAL: 75

DATA FOR TECHNICAL SCIENCES GRADE 12 

PAPER 2 (CHEMISTRY) 

TABLE 1: PHYSICAL CONSTANTS/TABEL 1: FISIESE KONSTANTES 

TABLE 2: FORMULAE/TABEL 2: FORMULES

TABLE 3: THE PERIODIC TABLE OF ELEMENTS/TABEL 3: DIE PERIODIEKE TABEL VAN ELEMENTE 

TABLE 4A: STANDARD REDUCTION POTENTIALS TABEL 4A: STANDAARD REDUKSIEPOTENSIALE 

TABLE 4B: STANDARD REDUCTION POTENTIALS TABEL 4B: STANDAARD REDUKSIEPOTENSIALE 

MARKING GUIDELINE

QUESTION/VRAAG 1 

1.1 C ✓✓ (2)

1.2 B ✓✓ (2)

1.3 D ✓✓ (2)

1.4 A ✓✓ (2) 

1.5 D ✓✓ (2) [10] 

QUESTION/VRAAG 2 

2.1 An atom or a group of atoms that determine the chemistry of a molecule. ✓✓ OR  An atom or a group of atoms that determine(s) the physical and chemical  properties of a group of organic compounds. 

2.2

2.2.1 E ✓ (1)

2.2.2 A and/en D ✓ (1)

2.2.3 F ✓ (1)

2.2.4 A, D and/en H ✓ (1)

2.2.5 A and/en D ✓ (1) 

2.3

2.3.1 pent-1-ene ✓ (accept 1-pentene/aanvaar 1-penteen) pent-1-een (1)

2.3.2 Propanone / Propanoon ✓ (1)

2.3.3 Hexanoic Acid / Heksanoësuur ✓ (1)

2.4

2.4.1 

2.4.2 ✓ (1) 

2.4.3 C5H11 ✓ (1)

2.4.4 Carboxyl group / Karboksiel-groep ✓ (1)

2.4.5 ✓✓ 

QUESTION/VRAAG 3 

3.1 The pressure exerted by a vapour at equilibrium with its liquid phases of a  substances are at equilibrium. ✓✓/ Die druk uitgeoefen deur ʼn damp in ewewig met sy vloeistof in ʼn geslote  sisteem. (2) 

3.2 

Marking criteria 

(3) 

3.3 The greater the molecular mass of organic compounds/alkanes, the lower the  vapour pressure. ✓/ Hoe groter die molekulêre massa van organiese verbindings/alkane, hoe laer is die dampdruk. (1) 3.4 Used as fuels/Word as brandstof gebruik ✓ (1) 

3.5

• Compound Z / pentane has 5 carbon atoms which makes it to have a longer  chain / greater molecular mass than compound Y / butane which has 4  carbon atoms which makes it to have a shorter chain/less molecular mass  than compound Z. ✓ 
  Verbinding Z / pentaan het 5 koolstofatome wat maak dat dit ʼn langer  ketting / groter molekulêre massa as verbinding Y het / butaan wat 4  koolstofatome het, wat maak dat dit ʼn korter ketting / minder molekulêre  massa as verbinding Z het.  
• The greater the molecular mass / longer the chain length the stronger the  Intermolecular forces / London forces in compound Z are stronger than those in compound Y which are weaker. ✓ 
  Hoe groter die molekulêre massa / langer die kettingslengte, hoe sterker is  die intermolekulêre kragte / Londonkragte in verbinding Z is sterker as die  in verbinding Y, wat swakker is. 
• More energy will be required to overcome intermolecular forces/London  forces in Compound Z than in compound Y where less energy will be  required to overcome intermolecular forces. ✓ 
  Meer energie sal benodig word om intermolekulêre kragte/Londenkragte in  verbinding Z te oorkom as in verbinding Y waar minder energie nodig sal  wees om intermolekulêre kragte te oorkom.  
• (Compound Z / pentane will have lower vapour pressure than compound  Y/butane which will have higher vapour pressure than Compound Z.) • (Verbinding Z / pentaan sal laer dampdruk hê as verbinding Y / butaan wat  hoër dampdruk as verbinding Z sal hê.) 

OR/OF 

• Compound Y / Butane has 4 carbon atoms which makes it to have a  shorter chain / lesser molecular mass than compound Z / pentane which  has 5 carbon atoms which makes it to have a longer chain / greater  molecular mass than compound Y.  
  Verbinding Y / Butaan het 4 koolstofatome wat maak dat dit ʼn korter  ketting / minder molekulêre massa het as verbinding Z / pentaan wat 5  koolstofatome het wat maak dat dit ʼn langer ketting / groter molekulêre  massa as verbinding Y het. 
• The lesser the molecular mass / shorter the chain the weaker the  intermolecular forces/London forces in compound Y than in Compound Z which are stronger.  
• Hoe kleiner die molekulêre massa / korter die ketting hoe swakker is die  intermolekulêre kragte/Londen kragte in verbinding Y as in verbinding Z wat sterker is.
• Less energy will be required to overcome intermolecular forces/London  forces in compound Y than in compound Z where more energy will be  required to overcome intermolecular forces.  
  Minder energie sal benodig word om intermolekulêre kragte/Londen kragte in verbinding Y te oorkom as in verbinding Z waar meer energie  benodig sal word om intermolekulêre kragte te oorkom. 
• (Compound Y / butane will have higher vapour pressure than compound  Z / pentane which will have lower vapour pressure than Compound Y.) (Verbinding Y / butaan sal hoër dampdruk hê as verbinding Z / pentaan  wat laer dampdruk as verbinding Y sal hê.) (3) 

3.6

3.6.1 Z ✓ (1)

3.6.2 X ✓ (1) 

3.6.3 X ✓ (1) [13]

QUESTION/VRAAG 4 

4.1 The temperature at which the vapour pressure is equal to the atmospheric  pressure. ✓✓ Die temperatuur waarby die dampdruk gelyk aan die atmosferiese druk is. (2)

4.2 Haloalkanes/alkyl halides/Haloalkane/alkielhaliede ✓ (1) 

4.3 (London forces and) Dipole-dipole intermolecular forces ✓/ (Londenkragte en) Dipool-dipool intermolekulêre kragte (1) 

4.4 The boiling point increase with an increase in the number of chlorine atoms  in haloalkanes. ✓/ Die kookpunt verhoog met ʼn toename in die aantal chlooratome in haloalkane. (1)

4.5

4.5.1 Tetrachloromethane / Tetrachlorometaan ✓ (1) 

4.5.2 One independent variable ✓ 
Accept same chain length / same number of carbons 

4.5.3 The vapour pressure of compound I will be lower than the vapour  pressure of compound L. ✓✓ 

OR 

The vapour pressure of compound L will be higher than the vapour  pressure of compound I. 

QUESTION/VRAAG 5 

5.1 Weaker/Swakker ✓ (1)

5.2 Propanol ✓ (1) 

5.3

5.3.1 Addition reaction/hydration ✓ 

5.3.2 Substitution reaction/halogenation/bromination ✓ 

5.3.3 Combustion/Oxidation ✓/ 

 5.4

5.4.1 ✓ 

5.4.2 Inorganic/Anorganies ✓ (1) 

5.4.3 It does not have carbon as the main element. ✓/ 

5.5

5.5.1 

5.5.2 Excess water /H₂O in concentration H₂SO₄ / Diluted sulphuric acid /  H₂SO₄ ✓

5.6

5.6.1 ✓ ✓

5.6.2 Oxygen (gas) / Suurstof (gas) ✓ (1) 

5.6.3 CO2 ✓ (1) [17] 

QUESTION/VRAAG 6 

6.1 Boron / B ✓ (1)

6.2 Three / Drie (3) ✓ (1) 

6.3 Free holes that are positively charged/positive holes. ✓

6.4 Semiconductor is a material that has electrical conductivity between that of a  conductor and an insulator. ✓✓

6.5 If the semiconductor is connected across the terminals of a cell, the electrons  in the valence band move from hole to hole. ✓ The absence of an electron creates the effect of a positive charge. ✓ 

6.6 Improves conductivity of the semiconductor ✓ 

6.7 P-type / P-tipe ✓ (1) [9] 

TOTAL: 75