Physical Sciences Grade 12 Paper 2 NSC November 2020 Memo

Downloaded from hlayiso.com SENIOR CERTIFICATE/SENIOR SERTIFIKAAT NATIONAL SENIOR CERTIFICATE/ NASIONALE SENIOR SERTIFIKAAT GRADE/GRAAD 12 PHYSICAL SCIENCES: CHEMISTRY (P2) FISIESE WETENSKAPPE: CHEMIE (V2) NOVEMBER 2020 MARKING GUIDELINES/NASIENRIGLYNE MARKS/PUNTE: 150 These marking guidelines consist of 17 pages./ Hierdie nasienriglyne bestaan uit 17 bladsye. Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 2 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 1/VRAAG 1 1.1 C  (2) 1.2 D  (2) 1.3 C  (2) 1.4 B  (2) 1.5 D  (2) 1.6 B  (2) 1.7 B  (2) 1.8 C  (2) 1.9 A  (2) 1.10 C  (2) [20] Copyright reserved/Kopiereg voorbehou

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 3 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 2/VRAAG 2 2.1.1 Ketones/Ketone  (1) 2.1.2 Pentanal/Pentanaal  Marking criteria/Nasienriglyne  Correct functional group,i.e. – ACCEPT/AANVAAR al / Korrekte funksionele groep 2,2-dimethylpropanal/2,2-dimethylpropanaal d.i. al  2-methylbutanal/2-metielbutanaal  Whole name correct/Hele 3-methylbutanal/3-metielbutanaal naam korrek  (2) 2.2.1 5 – bromo-2,3 – dimethylhexane/5 – bromo-2,3 – dimetielheksaan Marking criteria/Nasienriglyne:  Correct stem i.e. hexane./Korrekte stam d.i. heksaan.   All substituents (bromo and dimethyl) correctly identified./Alle substituente (bromo en dimetiel) korrek geïdentifiseer.   IUPAC name completely correct including numbering, sequence, hyphens and commas./IUPAC-naam heeltemal korrek insluitende volgorde, koppeltekens en kommas .  (3) 2.2.2 H H H Marking criteria/Nasienriglyne    Whole structure correct/Hele struktuur H C C C C C H 2 korrek: 2 H H  Only functional group correct:/Slegs H C H funksionele groep korrek: Max/Maks.: 1 2 H IF/INDIEN More than one functional group/Meer as een funksionele groep 0 2 (2) IF/INDIEN Molecular formula/Molekulêre formule 0 2 Condensed structural formula /Gekondenseerde struktuurformule 1 2 Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 4 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 2.3.1 The C atom bonded to the hydroxyl group is bonded to only one other C-atom.  (2 or 0) Die C-atoom wat aan die hidroksielgroep gebind is, is aan slegs een ander C-atoom gebind.(2 or 0) OR/OF The hydroxyl group/-OH/ is bonded to a C atom which is bonded to two hydrogens atoms. (2 or 0) Die hidroksielgroep/funksionele groep is gebind aan 'n C-atoom wat aan twee waterstofatome gebind is. (2 of 0) OR/OF The hydroxyl group/functional group/-OH is bonded to: a primary C atom / the first C atom (2 or 0) Die hidroksielgroep/funksionele groep/-OH aan 'n primêre C-atoom gebind / die eerste C-atoom gebind (2 of 0) OR/OF | The functional group (─ C - OH) is bonded to only one other C-atom. | | Die funksionele groep (─ C – OH) is aan slegs een ander C-atoom gebind. | (2) 2.3.2 Esterification/condensation  Verestering/esterifikasie/kondensasie (1) 2.3.3 Butanoic acid/Butanoësuur  (1) [12] Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 5 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 3/VRAAG 3 3.1 Marking criteria/Nasienriglyne If any one of the underlined key phrases in the correct context is omitted, deduct 1 mark./Indien enige van die onderstreepte frases in die korrekte konteks uitgelaat is, trek 1 punt af. The temperature at which the vapour pressure equals atmospheric (external) pressure.  Die temperatuur waar die dampdruk gelyk is aan atmosferiese (eksterne) druk. (2) 3.2 O C H (1) 3.3  Increase in the number of C-atoms increases molecular mass/size/chain length/surface area.   Strength of the intermolecular forces increases/More sites for London forces.   More energy is needed to overcome/break intermolecular forces.   Toename in aantal C-atome verhoog molekulêre massa/molekulêre grootte/kettinglengte/reaksie-oppervlak.  Sterkte van die intermolekulêre kragte verhoog./Meer punte vir Londonkragte.  Meer energie benodig om intermolekulêre kragte te oorkom/breek. (3) 3.4.1 C (1) 3.4.2 B Marking criteria/Nasienriglyne  Compare strength of intermolecular forces of A, B and C.   Compare boiling points/energy required to overcome intermolecular forces of alcohols/A and aldehydes/B.  OR Alcohols have the highest boiling point.  Compare boiling points/ energy required to overcome intermolecular force of aldehydes/B and alkanes/C . OR Alkanes have the lowest boiling point.  Vergelyk sterkte van intermolekulêre kragte van A, B en C.   Vergelyk kookpunte /energie benodig om intermolekulêre kragte van alkohole/A en aldehiede/B te oorkom.  OF Alkohole het die hoogste kookpunt.  Vergelyk kookpunte /energie benodig om intermolekulêre kragte van aldehiede/B en alkane/C. OF Alkane het die laagste kookpunt. Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 6 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne Aldehydes/B have (in addition to London forces) dipole-dipole forces which are stronger than London forces, but weaker than hydrogen bonds.  Therefore aldehydes/B have lower boiling points/require less energy to overcome intermolecular forces than alcohols/A,but higher boiling points / require more energy to overcome intermolecular forces than alkanes/C.  Aldehiede/B het (in toevoeging tot Londonkragte) dipool-dipoolkragte wat sterker is as Londonkragte, maar swakker is as waterstofbinding. Dus het aldehiede/B laer kookpunte/benodig minder energie om intermolekulêre kragte te oorkom as alkohole/A, maar hoër kookpunte/benodig meer energie om intermolekulêre kragte te oorkom as alkane/C. OR/OF Aldehydes/B have stronger intermolecular forces than alkanes, but weaker intermolecular forces than alcohols/A.  Therefore aldehydes/B have higher boiling points/ more energy required to overcome intermolecular forces than alkanes/C,  but lower boiling points/ less energy to overcome intermolecular forces than alcohols/A.  Aldehiede/B het sterker intermolekulêre kragte as alkane/C, maar swakker intermolekulêre kragte as alkohole/A. Dus het aldehiede/B laer kookpunte/ benodig minder energie om intermolekulêre kragte te oorkom as alkohole/A, maar hoër kookpunte/ benodig meer energie om intermolekulêre kragte te oorkom as alkane/C. (4) 3.5 Butanal  Marking criteria/Nasienriglyne Butanaal  Correct stem, i.e. but/Korrekte stam d.i. but   Whole name correct/Hele naam korrek  (2) 3.6 Pentan-1-ol  OR/OF 1-pentanol  (2) [15] QUESTION 4/VRAAG 4 4.1 Marking criteria/Nasienriglyne  Addition reaction / reaction of alkene / reaction of C – C double bond /reaction of unsaturated hydrocarbon Addisie reaksie / reaksie van ‘n alkeen /reaksie van C – C dubbelbinding/reaksie van ‘n onversadigde koolwaterstof.  (Addition of) hydrogen halide/HX/ hydrogen and halide.  (Addisie van) waterstofhalied/HX/waterstof en halied. The addition of a hydrogen halide/HX to an alkene. Die addisie van 'n waterstofhalied/HX aan 'n alkeen. (2) Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 7 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 4.2 H  H Marking criteria/Nasienriglyne   Whole structure correct: H C C C H 2 Hele struktuur korrek: 2 H H  Only functional group correct/Slegs funksionele groep korrek: Max/Maks: 1 2 (2) 4.3.1 Cracking/Kraking  (1) 4.3.2 C8H18  (1) 4.4 1,2–dibromo  propane  1,2-dibromopropaan/1,2-dibroompropaan (2) 4.5.1 H H H H H H     H C C C H + NaOH/H2O H C C C H + NaCℓ/HCℓ /KOH /KCℓ H Cℓ H H O H  H Marking criteria for the alcohol/Nasienriglyne vir die alkohol  Whole structure of alcohol correct/Hele struktuur van alkohol korrek: 2 2  Only functional group correct/Slegs funksionele groep korrek: 1 2 Notes/Aantekeninge:  If 1-chloropropane used as reactant, 2 marks for the primary alcohol. Indien 1-chloropropaan as reaktanse gebruik is, 2 punte vir die primêre alkohol.  Condensed or semi-structural formula: Max. 4 5 Gekondenseerde of semistruktuurformule: Maks. 4 5  Molecular formula/Molekulêre formule: 2 5  Any additional reactants or products: Max. 4 5 Enige addisionele reaktanse of produkte: Maks. 4 5  If arrow in completely correct equation omitted: Max. 4 5 Indien pyltjie in volledige korrekte vergelyking uitgelaat is: Maks. 4 5  The product NaCℓ/KCℓ/HCℓ must be marked in conjunction with reactant NaOH/KOH/H2O. Die produk NaCℓ/KCℓ/HCℓ moet in samehang met die reaktans NaOH/KOH / H2O nagesien word. (5) 4.5.2  (Mild) heat/(Matige) hitte   Dilute strong base/NaOH/LiOH/KOH OR water/H2O  Verdunde sterk basis/NaOH/LiOH/KOH OF water/H2O (2) [15] Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 8 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 5/VRAAG 5 5.1.1 (Reaction) rate/Reaksietempo  (1) 5.1.2 Surface area/state of division /particle size  Reaksie-oppervlak/toestand van verdeeldheid/deeltjie grootte (1) 5.2.1 (Decreasing gradient indicates) rate of reaction is decreasing.  (Afnemende gradiënt dui aan dat) reaksietempo afneem. (1) 5.2.2 (Gradient is zero, indicates) reaction rate is zero  (Gradiënt is nul, wat aandui dat) reaksietempo nul is. (1) 5.3 V ave rate/gem tempo = t 500 (  0) = = 8,33 (cm3∙s-1)  60(  0) (3) 5.4 Equal to/Gelyk aan  (1) 5.5 Greater than/Groter as  Experiment C/Eksperiment C:  Surface area of CaCO3 powder is greater than that of CaCO3 granules./ More particles are exposed /More particles with correct orientation   More effective collisions per unit time/Higher frequency of effective collisions.   Increase in reaction rate.  Reaksieoppervlak van CaCO3-poeier is groter (as die van CaCO3-korrels /Meer deeltjies met korrekte oriëntasie.  Meer effektiewe botsings per eenheid tyd./Hoër frekwensie van effektiewe botsings  Toename in reaksie tempo OR/OF Experiment A/Eksperiment A:  Surface area of CaCO3 granules is smaller/Fewer particles are exposed (than that of powdered CaCO3). Less particles with correct orientation   Less effective collisions per unit time./Lower frequency of effective collisions.   Decrease in reaction rate..  Reaksieoppervlak van CaCO3 is kleiner/Minder deeltjies is blootgestel (as die van die verpoeierde CaCO3)./ Minder deeltjies met korrekte oriëntasie  Minder effektiewe botsings per eenheidtyd./Laer frekwensie van effektiewe botsings.  Afname in reaksie tempo (4) Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 9 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 5.6 Marking criteria/Nasienriglyne: V  Divide volume by 25,7 in / Deel volume deur 25,7 in n = . VM If no substitution step shown, award mark for answer: 0,0195 mol Indien geen vervanging stap getoon is nie, ken punt toe vit antwoord: 0,0195 mol  Ratio/Verhouding: n(CO2) = n(CaCO3).  m  Substitute/Vervang 100 in n = or in ratio / of in verhouding.  M  Final answer/Finale antwoord: 1,95 g to/tot 2 g.  OPTION 1/OPSIE 1 OPTION 2/OPSIE 2 V 0,5 25,7 dm3 .........1 mol n(CO2 )  = Vm 25,7  0,5 dm3 ..........0,0195 mol  = 0,0195 mol 100 g ...........1 mol n(CaCO3) = n(CO2) = 0,0195 mol  x ....................0,0195 mol  m(CaCO3) = nM x = m(CaCO3) = 1,95 g  = 0,0195(100) = 1,95 g  OPTION 3/OPSIE 3 V 0,5 n(CO2 )  =  Vm 25,7 = 0,0195 mol 0,0195 mol CO2 ≡ 0,856 g CO2  m(CO2) produced : m(CaCO3) 44 g : 100 g  0,856 :x x = 1,95 g CaCO3 (4) [16] QUESTION 6/VRAAG 6 6.1 Products can be converted back to reactants.  Produkte kan omgeskakel word na reaktanse. OR/OF Both forward and reverse reactions can take place. Beide voor-en terugwaartse reaksies kan plaasvind. OR/OF A reaction which can take place in both directions. ‘n Reaksie wat in beide rigtings kan plaasvind. (1) 6.2.1 Remains the same/Bly dieselfde  (1) 6.2.2 Increases/Toeneem  (1) 6.3  (When pressure is increased) the reaction that leads to the smaller amount of gas / side with less molecules/number of moles is favoured.  (Wanneer die druk verhoog word,) word die reaksie wat tot die kleiner hoeveelheid gas /minder gas molekule/aantal mol lei, bevoordeel.  The reverse reaction is favoured.  Die terugwaartse reaksie word bevoordeel. (2) Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 10 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 6.4 Endothermic/Endotermies   Kc decreases with decrease in temperature.   Reverse reaction is favoured. / Concentration of reactants increases. / Concentration of products decreases./Yield decreases   Decrease in temperature favours an exothermic reaction.   Kc neem af met afname in temperatuur.  Terugwaartse reaksie word bevoordeel./Konsentrasie van reaktanse neem toe./Konsentrasie van produkte neem af./Opbrengs neem af  Afname in temperatuur bevoordeel 'n eksotermiese reaksie. OR/OF  Kc increases with increase in temperature.   Forward reaction is favoured. / Concentration of reactants decreases. / Concentration of products increases./Yield increases   Increase in temperature favours an endothermic reaction.   Kc neem toename met toename in temperatuur.  Voorwaartse reaksie word bevoordeel./Konsentrasie van produkte neem toe./Konsentrasie van reaktanse neem af./Opbrengs neem toe  Toename in temperatuur bevoordeel 'n endotermiese reaksie (4) 6.5 CALCULATIONS USING NUMBER OF MOLES Mark allocation  Correct Kc expression (formulae in square brackets).   Substitution of equilibrium concentrations into Kc expression.   Substitution of Kc value.   Multiply equilibrium concentrations of I2 and I by 12,3 dm3.  (OPTION 1)  Multiply equilibrium concentrations of I by 12,3 dm3 and divide equilibrium mol of I2 by 12,3 dm3. (OPTION 2)  Change in n(I) = n(I at equilibrium).   USING ratio/GEBRUIK verhouding: I2 : I = 1 : 2   Initial n(I2) = equilibrium n(I2) + change in n(I2).   Substitute 254 g·mol-1 as molar mass for I2.  Final answer: (26 g - 27,94 g).  BEREKENINGE WAT AANTAL MOL GEBRUIK Puntetoekenning:  Korrekte Kc-uitdrukking (formules in vierkanthakies).  Vervanging van ewewigskonsentrasies in Kc-uitdrukking.  Vervanging van Kc-waarde.   Vermenigvuldig ewewigskonsentrasies van I2 en I met 12,3 dm3.(OPSIE 1) Vermenigvuldig ewewigskonsentrasies van I met 12,3 dm3 en deel ewewigsmol I2 met 12,3 dm3(OPSIE 2)  Verandering in n(I) = n(I by ewewig)  GEBRUIK verhouding: I2 : I = 1 : 2   Aanvanklike n(I2) = ewewigs n(I2) + verandering in n(I2).  Vervang 254 g·mol-1 as molêre massa van I2.  Finale antwoord: (26 g – 27,94 g) Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 11 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne OPTION 1/OPSIE 1 [ I] 2 No Kc expression, correct substitution/Geen Kc- Kc   [I 2 ] uitdrukking, korrekte substitusie: Max./Maks. 8 9  3,76x10-3 =  4,79  103  2 Wrong Kc expression/Verkeerde Kc-uitdrukking: I 2  Max./Maks. 6  [I2] = 6,102 x 10 mol∙dm -3 -3 9 I2 I Initial mass (g) (0,1045)(254)  Aanvangsmassa (g) = 26,543 g  Initial quantity (mol) 0,1045 0 Aanvangshoeveelheid (mol) Change (mol)  Using 0,0295 0,0589  Verandering (mol) ratio  Quantity at equilibrium (mol)/ 0,0751 0,0589 Hoeveelheid by ewewig (mol) Equilibrium concentration (mol∙dm-3) x12,3  6,102 x 10-3 4,79 x 10-3 Ewewigskonsentrasie (mol∙dm-3) OPTION 2/OPSIE 2 I2 I Initial amount (moles) x 0 Aanvangshoeveelheid (mol) Change in amount (moles) ratio  0,0295  0,0589 verhouding Verandering in hoeveelheid (mol) Equilibrium amount (moles) hoeveelheid (mol) x - 0,0295 0,0589  Equilibrium concentration (mol∙dm-3) x  0,0295 x 12,3 and -3 Ewewigskonsentrasie (mol∙dm-3) 4,79 x 10 divide by 12,3 12,3 No Kc expression, correct substitution/Geen Kc- [ I] 2 Kc   uitdrukking, korrekte substitusie: Max./Maks. 8 [I 2 ] 9 -3 3,76x10 = 4,79  10   Wrong K expression/Verkeerde K -uitdrukking: 3 2 c c x  0,0295 Max./Maks. 6 9 12,3 x = 0,1045 mol  m = nM  = (0,1045)(254) = 26,543 g  Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 12 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne CALCULATIONS USING CONCENTRATION Mark allocation  Correct Kc expression (formulae in square brackets).   Substitution of equilibrium concentrations into Kc expression.   Substitution of Kc value   Change in n(I) = n(I at equilibrium).   USING ratio: I2 : I = 1 : 2   Initial [I2] = equilibrium [I2] + change in [I2].   Divide by 12,3 dm3.   Substitute 254 g·mol-1 as molar mass for I2.  Final answer 26,543 g.  BEREKENINGE WAT KONSENTRASIE GEBRUIK Puntetoekenning  Korrekte Kc-uitdrukking (formules in vierkanthakies).  Vervanging van ewewigskonsentrasies in Kc-uitdrukking.  Vervanging van Kc-waarde.  Verandering in n(I) = n(I by ewewig).  GEBRUIK verhouding I2 : I = 1 : 2  Aanvanklike [I2] = ewewigs [I2] + verandering in [I2].  Deel deur 12,3 dm3.   Vervang 254 g·mol-1 as molêre massa van I2.  Finale antwoord: 26,543 g OPTION 3/OPSIE 3 [ I] 2 No Kc expression, correct substitution/Geen Kc- Kc   [I 2 ] uitdrukking, korrekte substitusie: Max./Maks. 8 9 -3 3,76x10 = 4,79  10   3 2 I 2  Wrong Kc expression/Verkeerde Kc-uitdrukking: Max./Maks. 6 [I2] = 6,102 x 10-3 mol∙dm-3 9 I2 I -3 Initial concentration (mol∙dm ) Aanvangskonsentrasie (mol∙dm-3) 8,497x10-3 0  Using Change (mol∙dm-3) 2,395x10-3 4,79x10-3  ratio  Verandering (mol∙dm-3) Equilibrium concentration (mol∙dm-3) 6,102 x 10-3 4,79 x 10-3 Ewewigskonsentrasie (mol∙dm-3) m c MV m 8,497  10 3  (254)(12,3)  m  26,546 g  (9) [18] Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 13 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 7/VRAAG 7 7.1.1 Weak/Swak  - Ionises/Dissociates incompletely/partially (in water)  Ioniseer/Dissosieer/onvolledig/gedeeltelik (in water) (2) 7.1.2 OPTION 1/OPSIE 1 OPTION 2/OPSIE 2 pH = -log[H3O+]  [H3O+] = 10-pH  3,85  = -log[H3O+] = 10-3,85  [H3O+] = 1,41 x 10-4 mol∙dm-3  = 1,41 x 10-4 mol∙dm-3  (3) 7.1.3 Greater than/Groter as  (1) 7.1.4 CH3COO-(aq) + H2O(ℓ)  ⇌ CH3COOH(aq) + OH-(aq)  OR/OF CH3COONa(aq) + H2O(ℓ)  ⇌ CH3COOH(aq) + NaOH(aq)  Due to formation of hydroxide/OH- / the solution is basic/alkaline /pH > 7.  As gevolg van die vorming van hidroksied/OH- is die oplossing basies/ alkalies /pH > 7 (3) 7.2.1 Marking criteria/Nasienriglyne n c a  Va n a  Substitute/vervang: 1 x 0,0145 OR/OF 1 x 14,5 in c = /   V c b  Vb nb .  Use/Gebruik: n(CH3COOH) : n(NaOH) = 1:1   Final answer/Finale antwoord: 0,0145 mol  OPTION 1/OPSIE 1 n(NaOH)reacted = cV = 1(0,0145)  = 0,0145 mol n(CH3COOH)diluted = n(NaOH)  = 0,0145mol  (3) Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 14 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne 7.2.2 POSITIVE MARKING FROM 7.2.1./POSITEWE NASIEN VANAF VRAAG 7.2.1. Marking criteria/Nasienriglyne  Calculate mass/Bereken massa CH3COOH in 25 cm3 (1,13 g).  m  Formula/Formule: n = . M  Substitute/Vervang: M = 60 g∙mol-1.   n(CH3COOH)reacted/reageer = ninitial/begin - nunreacted/nie reageer   USE mol ratio/GEBRUIK molverhouding: n(CaCO3) : n(CH3COOH) = 1 : 2.  Substitution of/Vervanging van 100 g∙mol-1 in m = nM.  0,217  Calculate percentage/Bereken persentasie:  100  1,2  Final answer/Finale antwoord: 18,08%  (17,92 – 22,92) 4,52 m(CH3COOH) =  25  = 1,13 g 100 m n(CH3COOH)ini/aanv. =  M 1,13 = = 0,01883 mol 60 n(CH3COOH)rea = 0,01883  – 0,0145 = 0,0043 mol 1 n(CaCO3) = n(CH3COOH) 2 = 0,5(0,0043)  = 0,00217 mol m(CaCO3) = nM  = 0,00217(100) = 0,217 g 0,217 % CaCO3 =  100  1,2 = 18,08 %  (8) [20] Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 15 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 8/VRAAG 8 8.1 Provides path for movement of ions./Ensures(electrical)neutrality in the cell.  Verskaf pad vir beweging van ione./Verseker (elektriese) neutraliteit in die sel. (1) 8.2 (The electrode) where oxidation takes place/electrons are lost.  (Die elektrode) waar oksidasie plaasvind/elektrone verloor word. (2) 8.3 Mg/Magnesium  (1) 8.4.1 2H++ 2e- → H2  Marking criteria/Nasienriglyne H2 ← 2H+ + 2e- (2 ) 2H+ + 2e- ⇌ H2 (1 ) 2 2 H2 ⇌ 2H + 2e + - (0 ) + 2H + 2e ← H2 (0 ) 2 2  Ignore if charge omitted on electron./Ignoreer indien lading weggelaat op elektron.  If charge (+) omitted on H+/Indien lading (+) weggelaat op H+: Max./Maks: 1 - Example/Voorbeeld: 2H+ 2e → H2  2 (2) 8.4.2 Magnesium/Mg  (1) 8.5 OPTION 1/OPSIE 1 Notes/Aantekeninge  E cell   E reduction   E oxidation  Accept any other correct formula from the data sheet./Aanvaar enige ander korrekte formule  0  ( 2,36)  vanaf gegewensblad.  E cell  2,36 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 + -  2H + 2e → H2 E = 0 V  Mg(s)  Mg2+(aq) + 2e- E  = +2,36 V  Mg(s) + 2H+(aq)→ Mg2+(aq) + H2(g) E  = +2,36 V  (4) 8.6 H2 is a stronger reducing agent  than Cu  and therefore Cu2+/Cu ions are reduced/H2 is oxidised  Electrons flow from H2 to Cu. H2 is 'n sterker reduseermiddel as Cu en dus word Cu2+/Cu-ione gereduseer/H2 is geoksideer. Elektrone vloei vanaf H2 na Cu. (3) [14] Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 16 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 9/VRAAG 9 9.1 ANY ONE/ENIGE EEN:  The chemical process in which electrical energy is converted to chemical energy.  (2 or 0)  The use of electrical energy to produce a chemical change. (2 or 0)  Decomposition of an ionic compound by means of electrical energy. (2 or 0)  The process during which and electric current passes through a solution/ionic liquid/molten ionic compound. (2 or 0)  Die chemiese proses waarin elektriese energie omgeskakel word na chemiese energie. (2 of 0)  Die gebruik van elektriese energie om 'n chemiese verandering te weeg te bring. (2 of 0)  Ontbinding van 'n ioniese verbinding met behulp van elektriese energie. (2 of 0)  Die proses waardeur 'n elektriese stroom deur 'n oplossing/ioniese vloeistof/gesmelte ioniese verbinding beweeg. (2 of 0) (2) 9.2 Battery/cell/ power source  Battery/sel/kragbron (1) 9.3 Silver nitrate/AgNO3/ Silver ethanoate/CH3COOAg / Silver fluoride /AgF/ Silver perchlorate AgCℓO4.  Silwernitraat/AgNO3/ Silweretanoaat/CH3COOAg / Silwerfloried / AgF / Silwerperchloraat / AgCℓO4 (1) 9.4 Remains the same/Bly dieselfde  - Rate of oxidation is equal to the rate of reduction.  Tempo van oksidasie is gelyk aan die tempo van reduksie. (2) 9.5 Ag → Ag+ + e-  Notes/Aantekeninge Ag+ + e- ← Ag (2 ) Ag ⇌ Ag+ + e- (1 ) 2 2 + Ag ← Ag + e - (0 ) Ag + e ⇌ Ag + - ( 0 ) 2 2  Ignore if charge omitted on electron./Ignoreer indien lading weggelaat op elektron.  If charge (+) omitted on Ag+/Indien lading (+) weggelaat op Ag+: Example/Voorbeeld: Ag → Ag + e-  Max./Maks: (2) [8] Copyright reserved/Kopiereg voorbehou Please turn the page/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences/P2/Fisiese Wetenskappe/V2 17 DBE/November 2020 SC/NSC/SS/NSS – Marking Guidelines/Nasienriglyne QUESTION 10/VRAAG 10 10.1.1 (Liquid) Air/(Vloeibare)Lug  (1) 10.1.2 Natural gas/methane/oil/coal/coke Aardgas/metaan/olie/steenkool/kooks (1) 10.1.3 Iron/iron oxide/Fe/FeO  Yster/ysteroksied/Fe/FeO (1) 10.1.4 NH3/Ammonia/Ammoniak  (1) 10.1.5 Ostwald (process)/Ostwald(proses)  (1) 10.1.6 NH3 + HNO3  → NH4NO3  Bal  Marking criteria/Nasienriglyne  Reactants  Products  Balancing  Reaktanse Produkte Balansering  Ignore double arrows./Ignoreer dubbelpyle.  Marking rule 6.3.10./Nasienreël 6.3.10. (3) 10.2.1 NPK ratio/Ratio of primary nutrients  NPK-verhouding/Verhouding van primêre voedingstowwe (1) 10.2.2 OPTION 1/OPSIE 1 OPTION 2/OPSIE 2 4  x X x 20  = 2,315 kg m(P) = 2,315 kg 9 100 2,315 Mass of 1 part P = = 0,57575 4 X = 26  (26,04) Mass of N = (0,57575)(2) = 1,1575 kg Mass of K = (0,57575)(3) = 1,73625 kg Total mass of fertiliser: 1,1575 + 2,315 + 1,73625 = 5,20875 kg  5,20875 X= x 100 = 26,04  20 (3) [12] TOTAL/TOTAAL: 150 Copyright reserved/Kopiereg voorbehou