# Physical Sciences Grade 12 Paper 2 NSC June 2019 Memo

> Grade 12 Physical Sciences Paper 2 memorandum from the NSC June Exam 2019, 16 pages. Read online or download the free PDF.

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- Updated: 2026-09-27
- Subject: Physical Sciences
- Grade: Grade 12
- Document type: Memorandum
- Year: 2019
- Exam period: NSC June Exam
- Paper: 2
- Curriculum: CAPS
- Pages: 16

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             SENIOR CERTIFICATE EXAMINATIONS/
         NATIONAL SENIOR CERTIFICATE EXAMINATIONS
               SENIORSERTIFIKAAT-EKSAMEN/
          NASIONALE SENIORSERTIFIKAAT-EKSAMEN

                      PHYSICAL SCIENCES: CHEMISTRY (P2)
                      FISIESE WETENSKAPPE: CHEMIE (V2)

                                          2019

                      MARKING GUIDELINES/NASIENRIGLYNE

                                                                 MARKS/PUNTE: 150

                     These marking guidelines consist of 16 pages./
                      Hierdie nasienriglyne bestaan uit 16 bladsye.

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Physical Sciences/P2/Fisiese Wetenskappe/V2      2                                          DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

QUESTION 1/VRAAG 1

1.1      C                                                                                           (2)

1.2      A                                                                                           (2)

1.3      C                                                                                           (2)

1.4      A                                                                                           (2)

1.5      D                                                                                           (2)

1.6      C                                                                                           (2)

1.7      D                                                                                           (2)

1.8      D                                                                                           (2)

1.9      C                                                                                           (2)

1.10     A                                                                                           (2)
                                                                                                       [20]

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Physical Sciences/P2/Fisiese Wetenskappe/V2      3                                             DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

QUESTION 2/VRAAG 2

2.1         Unsaturated/Onversadig 
        -
            ANY ONE/ENIGE EEN:
            • C/It has a triple/multiple bond. 
              C/Dit het 'n trippelbinding/meervoudige-binding.
            • C/It has a triple/multiple bond between C atoms.
              C/Dit het 'n trippelbinding/meervoudige-binding tussen C-atome.
            • C/It does NOT contain the maximum number of H atoms bonded to C
              atoms.
              C/Dit bevat NIE die maksimum getal H-atome gebind aan C-atome nie.
            • Compound C is an alkyne./Verbinding C is ‘n alkyn.                                             (2)

2.2
2.2.1       D                                                                                               (1)

2.2.2       B                                                                                               (1)

2.2.3       C                                                                                               (1)

2.2.4       E                                                                                               (1)

2.3
2.3.1           C    C                                                                                      (1)

2.3.2
                 H     H    H     H           O   H       H
            H    C     C    C     C      O    C    C       C   H   

                 H     H    H     H                H       H
                                                                                                             (2)
            Marking criteria/Nasienriglyne:
            • Whole structure correct:
                Hele struktuur korrek:             2
                                                       2
            • Only functional group correct:/Slegs funksionele groep korrek: Max/Maks.: 1
                                                                                               2
            IF/INDIEN:
            •   More than one functional group/Meer as een funksionele groep:                 0
                                                                                          2
            •   If condensed or semi structural formula used:/Indien gekondenseerde of semi-
                struktuurformule gebruik:
                Max/Maks. 1
                             2

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Physical Sciences/P2/Fisiese Wetenskappe/V2      4                                           DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

2.3.3                  H                      Marking criteria/Nasienriglyne:
                                              • Three C atoms in longest chain. 
                  H    C H                       Drie C-atome in langste ketting.
                 H         H                   • One methyl substituent on C2. 
                                                  Een metielsubstituent op C2.
            H    C     C     C     H         IF/INDIEN
                                              Any error e.g. omission of H atoms, condensed or
                 H     H     H                semi structural formula/Enige fout bv weglating van
                                              H-atome, gekondenseerde of semi-
                                              struktuurformule.          Max/Maks.: 1
                                                                                      2                    (2)

2.4
2.4.1       2,3-dibromo-5-methylheptane/2,3-dibromo-5-metielheptaan
            Marking criteria/Nasienriglyne:
            •   Correct stem i.e. heptane./Korrekte stam d.i. heptaan. 
            •   All substituents (bromo and methyl) correctly identified./Alle substituente (bromo
                en metiel) korrek geïdentifiseer. 
            •   IUPAC name completely correct including numbering, sequence, hyphens and
                commas./IUPAC-naam heeltemal korrek insluitende nommering, volgorde,
                koppeltekens en kommas .                                                                  (3)

2.4.2       2C 4 H 10 + 13O 2   8CO 2 + 10H 2 O           Bal 
            Notes/Aantekeninge:
            •   Reactants          Products           Balancing 
                Reaktanse           Produkte            Balansering
            •   Ignore double arrows and phases./Ignoreer dubbelpyle en fases.
            •   Marking rule 6.3.10/Nasienreël 6.3.10.
            •   If condensed structural formulae used:/Indien gekondenseerde struktuur
                formules gebruik: Max/Maks. 2
                                                  3
            •   Accept coefficients that are multiples./Aanvaar koëffisiënte wat veelvoude is.              (3)
                                                                                                           [17]

QUESTION 3/VRAAG 3

3.1
3.1.1       Yes/Ja 
        -
            ANY ONE/ENIGE EEN:
            • Compounds have the same molecular mass. 
              Verbindings het dieselfde molekulêre massa.
            • Only one independent variable./Slegs een onafhanklike veranderlike.                          (2)

3.1.2       Functional group/Homologous series/Type of (organic) compound 
            Funksionele groep/Homoloë reeks/Tipe (organiese) verbinding                                    (1)

3.2         A/butane/butaan 
        -
            Lowest boiling point/weakest intermolecular forces. 
            Laagste kookpunt/swakste intermolekulêre kragte.                                               (2)

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Physical Sciences/P2/Fisiese Wetenskappe/V2      5                                         DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

3.3        Marking guidelines/Nasienriglyne
           • Type of IMF in A./Tipe IMK in A.
           • BOTH B and C have hydrogen bonding./BEIDE B en C het
              waterstofbinding.
           • Compare number of sites for hydrogen bonding in B and C./Vergelyk
              aantal punte vir waterstofbinding in B en C.
           • Compare strength of IMFs./Vergelyk sterkte van IMKe.
           • Compare energy required./Vergelyk energie benodig.
           •  Between molecules of butane/compound A are London forces/dispersion
              forces/induced dipole forces. 
           •  Molecules of compound B/propan-1-ol have one site for hydrogen
              bonding. 
           •  Molecules of compound C/ethanoic acid have two/more sites for
              hydrogen bonding. 
           •  Strength of intermolecular forces increases from compound A/butane to
              compound B/propan-1-ol to compound C/ethanoic acid. 
              OR
              Intermolecular forces in compound A/butane are the weakest and
              intermolecular forces in compound C/ethanoic acid are the strongest.
           •  More energy is needed to overcome/break intermolecular forces in
              compound C than in the other two compounds. 

           •   Tussen molekule van butaan/verbinding A is Londonkragte/dispersie-
               kragte/geïnduseerde dipoolkragte. 
           •   Molekule van verbinding B/propan-1-ol het een punt vir waterstof-
               bindings. 
           •   Molekule van verbinding C/etanoësuur het twee punte vir waterstof-
               bindings. 
           •   Sterkte van intermolekulêre kragte neem toe van verbinding A/butaan na
               verbinding B/propan-1-ol na verbinding C/etanoësuur. 
               OF
               Intermolekulêre kragte tussen propaan is die swakste en intermolekulêre
               kragte in verbinding C is die sterkste.
           •   Meer energie word benodig om intermolekulêre kragte in verbinding C as
               in die ander twee verbindings te oorkom/breek.                                           (5)

3.4        Butan-1-ol 
       -
           Longer chain length./Larger molecule./Larger molecular mass./Larger
           molecular size./Stronger intermolecular forces./Larger surface area.
           Langer kettinglengte./Groter molekuul./Groter molekulêre massa/Groter
           molekuul./Sterker intermolekulêre kragte./Groter oppervlakte.                                  (2)
                                                                                                         [12]

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Physical Sciences/P2/Fisiese Wetenskappe/V2      6                                           DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

QUESTION 4/VRAAG 4

4.1
4.1.1     Addition (polymerisation)/Addisie-(polimerisasie)                                             (1)

4.1.2     Ethene/eteen                                                                                  (1)

4.1.3     Polyethene/polythene 
          Poli-eteen/politeen                                                                            (1)

4.2
4.2.1     Dehydration/elimination 
          Dehidrasie/dehidratering/eliminasie                                                            (1)

4.2.2     Catalyst/dehydrating agent/causes dehydration/removes water molecules 
          Katalisator/dehidreermiddel/veroorsaak dehidrasie/verwyder watermolekule                       (1)

4.2.3     Prop-1-ene/propene/1-propene  (2 or 0)
          Prop-1-een/propeen/1-propeen (2 of 0)                                                          (2)

4.2.4          H     H     H
                                        
         H     C     C     C     Cℓ         

               H     H     H

          Marking criteria/Nasienriglyne:
          • Whole structure correct:
             Hele struktuur korrek:              2
                                                     2
          • Only functional group correct:/Slegs funksionele groep korrek: Max/Maks.: 1
                                                                                             2
          IF/INDIEN:
          • More than one functional group/Meer as een funksionele groep:                0
                                                                                      2
          • If condensed or semi structural formula used:/Indien gekondenseerde of semi-
            struktuurformule gebruik:
            Max/Maks. 1
                         2                                                                               (2)

4.2.5     Addition/Hydration 
          Addisie/Hidrasie/Hidratering                                                                   (1)

4.2.6     Propan-2-ol/2-propanol          Marking criteria/Nasienriglyne:
                                            • Correct stem and functional group i.e
                                              propanol/Korrekte stam en funksionele groep d.i
                                              propanol 
                                            • Name completely correct/Naam volledig korrek:
                                              Propan-2-ol/2-propanol                                    (2)
                                                                                                         [12]

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Physical Sciences/P2/Fisiese Wetenskappe/V2      7                                          DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

QUESTION 5/VRAAG 5

5. 1        NOTE/LET WEL
            Give the mark for per unit time only if in context of reaction rate.
            Gee die punt vir per eenheidtyd slegs indien in konteks met reaksietempo.
            ANY ONE/ENIGE EEN
            • Change in concentration  of products/reactants per (unit) time. 
              Verandering in konsentrasie van produkte/reaktanse per (eenheid) tyd.

            •   Change in amount/number of moles/volume/mass of products or reactants
                per (unit) time.
                Verandering in hoeveelheid/getal mol/volume/massa van produkte of
                reaktanse per (eenheid) tyd.
            •   Amount/number of moles/volume/mass of products formed/reactants used
                per (unit) time.
                Hoeveelheid/getal mol/volume/massa van produkte gevorm/reaktanse
                gebruik per (eenheid) tyd.

            •   Rate of change in concentration/amount/number of moles/volume/mass.
                Tempo van verandering in konsentrasie/ hoeveelheid/getal mol/
                volume/massa.  (2 or/of 0)                                                              (2)

5.2
5.2.1       Rate of the reaction/Reaksietempo                                                            (1)

5.2.2
            Criteria for conclusion/Kriteria vir gevolgtrekking:
            Dependent (reaction rate) and independent (concentration ) variables correctly
            identified./Afhanklike(reaksietempo) en onafhanklike (konsentrasie)                 
        -   veranderlikes korrek geïdentifiseer.
            Relationship between the independent and dependent variables correctly stated.
            Verwantskap tussen die afhanklike en onafhanklike veranderlikes korrek              
            genoem.

            Example/Voorbeeld:
            Reaction rate increases with increase in concentration./Reaction rate
            is proportional to concentration.
            Reaksietempo neem toe met toename in konsentrasie./Reaksietempo
            is eweredig aan konsentrasie.
            IF/INDIEN
            DIRECTLY proportional/DIREK eweredig:           Max/Maks.: 1
                                                                           2                              (2)

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Physical Sciences/P2/Fisiese Wetenskappe/V2      8                                                             DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

5.3
5.3.1     Activation energy/(The boundary line for the) molecules with
          (adequate) kinetic energy to make effective collisions. 
          Aktiveringsenergie/(Die grenslyn vir die) molekule met (genoeg)
          kintiese energie vir effektiewe botsings.                                                                          (1)

5.3.2     B                                                                                                                 (1)

5.3.3     •       At a higher temperature particles move faster/have a higher kinetic
                  energy. 
                  By 'n hoër temperatuur beweeg die deeltjies vinniger/het die deeltjies
                  hoër kinetiese energie.
          •       More molecules have enough/sufficient (kinetic) energy. 
                  Meer molekule het genoeg/voldoende (kinetiese) energie.
                  OR/OF
                  More molecules have (kinetic) energy equal to or greater than activation
                  energy.
                  Meer molekule het (kinetiese) energie gelyk aan of groter as
                  aktiveringsenergie.
          •       More effective collisions per unit time/second./Increased frequency of
                  effective collisions.
                  Meer effektiewe botsings per eenheidtyd/sekonde./Frekwensie van
                  effektiewe botsings neem toe.
          •       Reaction rate increases. 
                  Reaksietempo neem toe.                                                                                     (4)

5.4       Curve Y/it was obtained for the reaction where a catalyst was added. 
          Kurwe Y/dit is vir die reaksie waar 'n katalisator bygevoeg is, verkry.

          OR/OF
          Curve X was obtained for the reaction in the absence of a catalyst.
          Kurwe X is verkry vir die reaksie sonder 'n katalisator.                                                           (1)

5.5       Marking guidelines/Nasienriglyne
                                                         m             n
              •   Any formula/Enige formule: n =             or/of c =   
                                                         M             V
              •   Substitute/Vervang 0,1 dm3 in n = cV 
              •   Use mole ratio/Gebruik molverhouding:
                  n(S) expected/verwag = ½n(HCℓ) used/gebruik 
                                                                                  m
              •   Substitution of/Vervanging van 32 g∙mol-1 in n =                  
                                                                                  M
              •   SUBSTITUTE in/VERVANG in:
                   n(S)produced / berei              m(S)produced / berei
                                          x 100 /                            x 100 
                  n(S)exp ected /verwag             m(S) exp ected /verwag
              •   Final answer/Finale antwoord: 56,25% to 60% 

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Physical Sciences/P2/Fisiese Wetenskappe/V2      9                                                           DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

          OPTION 1/OPSIE 1                                       OPTION 2/OPSIE 2
          n(HCℓ) used/gebruik = cV                              n(HCℓ) used/gebruik = cV 
                             = 0,2 x 0,1                                             = 0,2 x 0,1 
                             = 0,02 mol                                               = 0,02 mol

          n(S) expected/verwag = ½n(HCℓ) used/gebruik            n(S) expected/verwag = ½n(HCℓ) used/gebruik
                              = ½(0,02)                                              = ½(0,02) 
                              = 0,01 mol                                              = 0,01 mol

                               m                                 m(S) expected/verwag = nM
          n(S) produced/berei =
                               M                                                      = (0,01)(32) 
                               0,18                                                   = 0,32 g
                             =
                                32 
                             = 0,0056 mol                                                m(S) prod/berei
                                                                 %yield/opbrengs =                         × 100
                                                                                         m(S) exp/verwag
                                      n(S)prod / berei                                 0,18
          %yield/opbrengs =                              × 100                       =      x 100 
                                      n(S)exp/verwag                                   0,32
                                    0,0056                                           = 56,25% 
                                  =        x 100            
                                      0,01
                                  = 56,25%                                                                              (6)
                                                                                                                        [18]
QUESTION 6/VRAAG 6
6.1       Reversible reaction/Both forward and reverse reactions can take
          place./Products can be converted back to reactants. 
          Omkeerbare reaksie/Beide voorwaartse en terugwaartse reaksies kan
          plaasvind./Produkte kan terugverander word na reaktanse.                                                      (1)
6.2       To favour the forward reaction/production of ammonia./To increase the yield
          of ammonia./Prevent the decomposition of NH 3 . 
          Om die voorwaartse reaksie/produksie van ammoniak te bevoordeel./Om die
          ammoniak-opbrengs te verhoog./Voorkom die ontbinding van NH 3.                                                (1)
6.3       20(%)                                                                                                        (1)

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                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

6.4
6.4.1     At 500 °C lower yield of ammonia:
          • The (forward) reaction is exothermic./Reverse reaction is endothermic. 
             Die (voorwaartse) reaksie is eksotermies./Terugwaartse reaksie is
             endotermies.
          • An increase in temperature favours the endothermic reaction. 
             'n Toename in temperatuur bevoordeel die endotermiese reaksie.
          • The reverse reaction is favoured.
             Die terugwaartse reaksie word bevoordeel.
          OR/OF
          At 350 °C higher yield of ammonia:
          • The (forward) reaction is exothermic./Reverse reaction is endothermic. 
             Die (voorwaartse) reaksie is eksotermies./Terugwaartse reaksie is
             endotermies.
          • A decrease in temperature favours the exothermic reaction. 
             'n Afname in temperatuur bevoordeel die eksotermiese reaksie.
          • The forward reaction is favoured. 
             Die voorwaartse reaksie word bevoordeel.                                                    (3)

6.4.2     At 350 atm higher yield of ammonia:
          • An increase in pressure favours the reaction that produces the lower
             number of moles/number of molecules/volume of gas. 
             'n Toename in druk bevoordeel die reaksie wat die kleiner aantal
             mol/aantal molekule/volume gas lewer.
          • The forward reaction is favoured. 
             Die voorwaartse reaksie word bevoordeel.

          OR/OF
          At 150 atm lower yield of ammonia:
          • A decrease in pressure favours the reaction that produces the higher
             number of moles/number of molecules/volume of gas. 
             'n Afname in druk bevoordeel die reaksie wat die groter aantal mol/aantal
             molekule/volume gas lewer.
          • Reverse reaction is favoured. 
             Die terugwaartse reaksie word bevoordeel.                                                   (2)

6.5
6.5.1     1 mol N 2 reacts with 3 mol H 2 to produce 2 mol NH 3
          ∴ 2 mol N 2 reacts with 6 mol H 2 to produce 4 (mol) NH 3  (2 or 0)

          1 mol N 2 reageer met 3 mol H 2 om 2 mol NH 3 te lewer
          ∴ 2 mol N 2 reageer met 6 mol H 2 om 4 (mol) NH 3 te vorm (2 of 0)                             (2)

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                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

6.5.2     POSITIVE MARKING FROM QUESTION 6.5.1.
          Marking criteria/Nasienriglyne:
          •   Calculate 35% of 4 mol NH 3 (answer from Q6.5.1). 
          •   Use mol ratio/Gebruik molverhouding n(N 2 ) : n(H 2 ) : n(NH 3 ) = 1 : 3 : 2 
          •   Equilibrium/Ewewig n(N 2 ) = initial/aanvanklike n(N 2 ) - ∆n(N 2 ) 
              Equilibrium/Ewewig n(H 2 ) = initial/aanvanklike n(H 2 ) - ∆n(H 2 )
          •   Divide by/Deel deur 0,5 dm3. 
          •   Correct K c expression (formulae in square brackets). 
              Korrekte K c uitdrukking (formules in vierkantige hakies).
          •   Substitution of concentrations into correct K c expression. 
              Vervanging van konsentrasies in korrekte K c -uitdrukking.
          •   Final answer/Finale antwoord: 0,002 
              Range/Gebied: 0,00155 to 0,002 (1,55 x 10-3 to 2 x 10-3)

                      35
          n(NH 3 ) =     ×4
                     100
                   = 1,4 mol

                                                           N2        H2        NH 3
           Initial amount (moles)
                                                            6         6          0
           Aanvangs hoeveelheid (mol)
           Change in amount (moles)                                                       ratio 
                                                           0,7       2,1        1,4       verhouding
           Verandering in hoeveelheid (mol)
           Equilibrium amount (moles)                                      
                                                           5,3       3,9        1,4
           hoeveelheid (mol)
           Equilibrium concentration (mol∙dm-3)                                            Divide by
                                                          10,6       7,8        2,8
           Ewewigskonsentrasie (mol∙dm-3)                                                  0,5 dm3 

                                              No Kc expression, correct substitution/Geen Kc-
                [NH3 ] 2
          Kc =                               uitdrukking, korrekte substitusie: Max./Maks. 6
               [H2 ]3 [N2 ]                                                                   7
                  (2,8) 2                     Wrong Kc expression/Verkeerde Kc-uitdrukking:
             =                
               (7,8) 3 (10,6)                 Max./Maks. 4
                                                           7
             = 0,002                                                                                        (7)
                                                                                                            [17]

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Physical Sciences/P2/Fisiese Wetenskappe/V2     12                                         DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

QUESTION 7/VRAAG 7

7.1      A base forms hydroxide ions (OH-) in water/aqueous solution. 
         'n Basis vorm hidroksiedione (OH-) in water/waterige oplossing.
         IF/INDIEN:
         A base ionises to form hydroxide ions (OH-). 
         'n Basis ioniseer om hidroksiedione (OH-) te vorm.                   Max./Maks. 1
                                                                                             2           (2)

7.2       A strong base ionises/dissociates completely  and a weak base
          ionises/dissociates incompletely. 
          'n Sterk basis ioniseer/dissosieer volledig en 'n swak basis ioniseer/dissosieer
          onvolledig.                                                                                    (2)

7.3       HCO 3− (aq) + H 2 O(ℓ)  ⇌ H 2 CO 3 (aq) + OH − (aq)          Bal. 
          Accept/Aanvaar
          NaHCO 3 (aq) + H 2 O(ℓ) ⇌ H 2 CO 3 (aq) + NaOH(aq)
          Notes/Aantekeninge:
          •   Reactants/Reaktanse        Products/Produkte        Balancing/Balansering 
          •   Ignore single arrow./Ignoreer enkelpyl.
          •   Marking rule 6.3.10./Nasienreël 6.3.10.
          •   Ignore phases/Ignoreer fases.                                                              (3)

7.4
7.4.1     pH = -log[H 3 O+] 
             = -log (0,2) 
             = 0,70        (0,699)                                                                      (3)

7.4.2     Titration of a weak base and a strong acid. 
          Titrasie van 'n swak basis en 'n sterk suur.

          OR/OF
          The endpoint will be at pH < 7./Die eindpunt sal by 'n pH < 7.                                 (1)

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Physical Sciences/P2/Fisiese Wetenskappe/V2     13                                         DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

7.4.3     Marking guidelines/Nasienriglyne:
                                                 n     m c × Va n a       m
          •    Any formulae/Enige formule: c =     /n = / a      =   /c =    
                                                 V     M c b × Vb nb      MV
          •    Substitute/Vervang 0,2 mol∙dm-3 & 20 x 10-3/0,02 dm3 or 20 cm3. 
          •    Use mol ratio/Gebruik molverhouding n(XHCO 3 ) : n(HCℓ) = 1 : 1 
          •    Substitute/Vervang n(XHCO 3 ) or/of c(XHCO 3 ) AND/EN 0,4 g. 
                               -1
          •    M(X) = 39 g∙mol 
          •    X = K/potassium/kalium. 
          OPTION 1/OPSIE 1                                           OPTION 2/OPSIE 2
                   n                                                  c a × Va n a
          c(HCℓ) =                                                            =    
                   V                                                 c b × Vb n b
                        n                                             0,2 × 20  1
          ∴ 0,2 =                                                               = 
                    20 × 10 −3                                       c b × 100    1
          n(HCℓ) = 4 x 10-3 mol
                                                                     c b = 0,04 mol∙dm-3
          n(XHCO 3 ) = n(HCℓ) 
                     = 4 x 10-3 mol                                            m
                                                                     c( XHCO3 ) =
                                                                              MV
               m                                                            0,4
          n=                                                     ∴ 0,04 =         
               M                        1 mol                  →           M(0,1)
                     0,4                M(XHCO 3 ) 4 x 10-3 mol M(XHCO 3 ) = 100 g∙mol-
          ∴ 4 × 10 −3 =                → 0,4 g                 1
                     M                                        -1
          M = 100 g∙mol-1               M(XHCO 3 ) = 100 g∙mol
                                                                 M(XHCO 3 ) = M(X) + 61
          M(XHCO 3 ) = M(X) +           M(XHCO 3 ) = M(X) + 61              = 100
          61                                       = 100         ∴M(X)  = 39 g∙mol-1 
                                                         -1
                     = 100              ∴M(X) = 39 g∙mol 
          ∴ M(X) = 39 g∙mol-1                                   X=K
                                        X=K                     OR/OF
          X=K                          OR/OF                    potassium/kalium
          OR/OF                         potassium/kalium
          potassium/kalium                                                                                (6)
                                                                                                         [17]

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Physical Sciences/P2/Fisiese Wetenskappe/V2     14                                                DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

QUESTION 8/VRAAG 8
8.1       It is a conductor of electricity/a solid to connect wires to./Pt is inert or
          unreactive. 
          Dit is 'n geleier van elektrisiteit/'n vaste stof waaraan drade geskakel kan
          word./Pt is inert of onreaktief.
          OR/OF
          Cℓ−(aq) and chlorine gas are not solids and cannot be used as an electrode.
          Cℓ−(aq) en chloorgas is nie vaste stowwe nie en kan nie as 'n elektrode
          gebruik word nie.                                                                                     (1)
8.2
8.2.1     Chemical (energy) to electrical (energy) 
          Chemiese (energie) na elektriese (energie)                                                            (1)
8.2.2    Cℓ 2 + 2e- → 2Cℓ− 
         Marking guidelines/Nasienriglyne
         • Cℓ 2 + 2e- ⇌ 2Cℓ−      1                    2Cℓ− ⇌ Cℓ 2 + 2e-       0
                                    2                                            2
               −
           2Cℓ ← Cℓ 2 + 2e  -     2                       −-
                                                      2Cℓ → Cℓ 2 + 2e    -    0
                                    2                                            2
         • Ignore if charge omitted on electron./Ignoreer indien lading weggelaat op elektron.
         • If charge (-) omitted on Cℓ−/Indien lading (-) weggelaat op 2Cℓ−:
           Max./Maks: 1                      Example/Voorbeeld: Cℓ 2 + 2e- → 2Cℓ 
                          2                                                                                      (2)
                             
8.2.3     Cr(s) | Cr3+(aq) || Cℓ 2 (g) | Cℓ− (aq) | Pt(s) 
          OR/OF
          Cr(s) | Cr3+(1 mol∙dm-3) || Cℓ 2 (g) | Cℓ− (1 mol∙dm-3) | Pt(s)
          Accept/Aanvaar:
          Cr | Cr3+ || Cℓ 2 | Cℓ− | Pt                                                                          (3)

8.3       OPTION 1/OPSIE 1                       Notes/Aantekeninge
            θ
          E cell     θ
                 = E reduction     θ
                               − E oxidation    • Accept any other correct formula from the data
                                                 sheet./Aanvaar enige ander korrekte formule
                 = 1,36 − ( −0,74)                 vanaf gegewensblad.
            θ
          E cell = 2,10 V                       • Any other formula using unconventional
                                                   abbreviations, e.g. E° cell = E° OA - E° RA followed
                                                   by correct substitutions:/Enige ander formule
                                                   wat onkonvensionele afkortings gebruik bv.
                                                   E° sel = E° OM - E° RM gevolg deur korrekte
                                                   vervangings : 3
                                                                     4
         OPTION 2/OPSIE 2
         Cℓ 2 + 2e- → 2Cℓ−                                    E θ = 1,36 V 
         
         Cr(s)  Cr3+(aq) + 3e-                               E θ = +0,74 V 
          2Cr(s) + 3Cℓ 2 (g) → 2Cr3+(aq) + 6Cℓ−(aq)           E θ = +2,10 V                                   (4)

8.4       Increases/Verhoog                                                                                  (2)
                                                                                                               [13]
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Physical Sciences/P2/Fisiese Wetenskappe/V2     15                                         DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

QUESTION 9/VRAAG 9

9.1       Electrolytic/Elektrolities                                                                    (1)

9.2      2H 2 O + 2e- → H 2 + 2OH- 
         Marking guidelines/Nasienriglyne
         • 2H 2 O + 2e- ⇌ H 2 + 2OH- 1                  H 2 + 2OH- ⇌ 2H 2 O + 2e-          0
                                               2                                             2
                        -
           H 2 + 2OH ← 2H 2 O + 2e        -   2                      -
                                                        H 2 + 2OH → 2H 2 O + 2e       -    0
                                                2                                            2
         • Ignore if charge omitted on electron./Ignoreer indien lading weggelaat op elektron.
         • If charge (-) omitted on OH-/Indien lading (-) weggelaat op OH-:
           Max./Maks: 1
                                                                          -
                                     Example/Voorbeeld: 2H 2 O + 2e → H 2 + 2OH
                          2
                                                                                                          (2)

9.3
9.3.1     Chlorine (gas) / Cℓ 2 /Chloor(gas)                                                             (1)

9.3.2     P&Y                                                                                           (2)

9.4       Cathode/Katode 
          Reduction takes place here./Gains electrons.
          Reduksie vind hier plaas./Wins van elektrone.                                                   (2)

9.5       CuCℓ 2 (aq)  → Cu(s) + Cℓ 2 (g)                Bal 
          OR/OF
                          -
          Cu2+(aq) + 2Cℓ → Cu(s) + Cℓ 2 (g)
          Notes/Aantekeninge:
          •   Reactants/Reaktanse        Products/Produkte        Balancing/Balansering 
          •   Ignore double arrows./Ignoreer dubbelpyle.
          • Marking rule 6.3.10./Nasienreël 6.3.10.
          • Ignore phases/Ignoreer fases.                                                                  (3)
                                                                                                          [11]

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Physical Sciences/P2/Fisiese Wetenskappe/V2     16                                      DBE/2019
                           SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne

QUESTION 10/VRAAG 10
10.1
10.1.1    II – IV – III - I                                                                        (1)
10.1.2    2NH 3 + H 2 SO 4  → (NH 4 ) 2 SO 4             Bal 
          Notes/Aantekeninge:
          •   Reactants/Reaktanse        Products/Produkte        Balancing/Balansering 
          •   Ignore double arrows./Ignoreer dubbelpyle.
          •   Marking rule 6.3.10./Nasienreël 6.3.10.                                               (3)

10.1.3    Vanadium pentoxide/Vanadiumpentoksied                                                    (1)
10.1.4    SO 3 (g) + H 2 SO 4 → H 2 S 2 O 7            Bal 
          Notes/Aantekeninge:
          •   Reactants/Reaktanse        Products/Produkte        Balancing/Balansering 
          •   Ignore double arrows./Ignoreer dubbelpyle.
          •   Marking rule 6.3.10./Nasienreël 6.3.10.                                               (3)
10.1.5    Sulphuric acid will form (white) mists./The reaction is very exothermic/gives
          off too much heat./Corrosive reaction. 
          Swawelsuur sal (wit) mis vorm./Die reaksie is té eksotermies/gee te veel
          warmte af./Vretende reaksie.                                                              (1)

10.2      Marking criteria/Nasienriglyne:
          • Calculate m(fertiliser)./Bereken m(kunsmis). 
                                             2
          • Use ratio/gebruik verhouding:        /m(P) = ½m(K) 
                                            X+3
          • Use/Gebruik m(K) = 3,33 kg 
          • Final answer/Finale antwoord: 3 

          OPTION 1/OPSIE 1                          OPTION 3/OPSIE 3
                           20                                       20
          m(fertiliser) =     × 50                 (fertiliser) =     × 50 
                          100                                      100
                        = 10 kg                                  = 10 kg

                       2                            m(P) = ½m(K) 
              m(K) =      × 10                           = ½(3,33) = 1,665 kg
                      X+3
                       2
          ∴ 3,33  =      × 10                      m(X) = 10 – 3,33 – 1,665
                      X+3
                                                         = 5,005
              ∴X=3
          OPTION 2/OPSIE 2                          N : P : K = 5,005 : 1,665 : 3,33
                    2  20                                    =3:1:2
          m(K) =       ×     x 50  = 3,33 
                  X + 3 100                         ∴X=3
          X=3                                                                                      (4)
                                                                                                   [13]

                                                                              TOTAL/TOTAAL:        150

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