Physical Sciences Grade 12 Paper 2 EC June 2018 Memo

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE/ NASIONALE SENIOR SERTIFIKAAT GRADE/GRAAD 12 JUNE/JUNIE 2018 PHYSICAL SCIENCES P2/FISIESE WETENSKAPPE V2 MARKING GUIDELINE/NASIENRIGLYN MARKS/PUNTE: 150 This marking guideline consists of 10 pages./ Hierdie nasienriglyn bestaan uit 10 bladsye. 1

Downloaded from hlayiso.com QUESTION/VRAAG 1 1.1 D  (2) 1.2 C  (2) 1.3 B  (2) 1.4 D  (2) 1.5 B  (2) 1.6 D  (2) 1.7 A  (2) 1.8 A  (2) 1.9 B  (2) 1.10 D  (2) [20] QUESTION/VRAAG 2 2.1.1 Organic compound that consist of carbon and hydrogen atoms only.  Organiese verbindings wat slegs uit koolstof- en waterstofatome bestaan. (2 or/of 0) (2) 2.1.2 Alkanes /Alkane (1) 2.1.3 C2H5  (1) 2.1.4 2C4H10 + 13O2  → 8CO2 + 10H2O  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 struktuurformules gebruik: Max./Maks. 2/3 (3) 2.1.5 EXOTHERMIC /EKSOTERMIES (1) 2.1.6 The chemical process in which longer chain hydrocarbon molecules are broken into shorter more useful molecules.  Die chemiese proses waarin langer ketting koolwaterstofmolekules afgebreek word in korter meer bruikbare molekules. (2) 2

Downloaded from hlayiso.com 2.1.7 H H Marking criteria/Nasienriglyne: • Whole structure correct/ Hele struktuur korrek: 2/2 • Only functional group correct. C C  Slegs funksionele groep korrek. Max./Maks.. 1/2 H H (2) 2.1.8 CATALYTIC/KATALITIES (1) 2.1.9 UNSATURATED/ONVERSADIG Contains double bonds OR multiple bonds between C atoms. Bevat dubbelbindings OF meervoudige bindings tussen C-atome. (2) 2.1.10 2,3-dimethylbut-2-ene/2,3-dimethyl-2-buteen 2,3-dimetielbut-2-een/2,3-dimetiel-2-buteen Marking Criteria/Nasienriglyne: • Correct stem i.e but-2-ene/2-butene. Korrekte stam bv.but-2-een/2-buteen.  • Substituent dimethyl correctly identified.  Substituent dimetiel korrek geïdentifiseer. • Substituents correctly numbered, hyphens and commas correctly used.  Substituente korrek genommer, koppeltekens en kommas korrek gebruik. (3) 2.2.1 H H C H H H H H  H C C C C C C C H  C H H H H H C H Marking criteria/Nasienriglyne: • Functional group/Funksionele groep.  H C H • Methyl and ethyl substituents / Metiel en etiel substituente  H • Whole structure correct/ Hele struktuur korrek  3/3 (3) 2.2.2 Pentan-2-one/2-pentanone Pentan-2-oon/2-pentanoon (2) [23] 3

Downloaded from hlayiso.com QUESTION/VRAAG 3 3.1 A bond or an atom or a group of atoms that determine(s) the physical and chemical properties of a group of organic compounds.  ʼn Binding of ʼn atoom of ʼn groep atome wat die fisiese en chemiese eienskappe van ʼn groep organiese verbindings bepaal. (2 or/of 0) (2) 3.2.1 Aldehyde /Aldehied (1) 3.2.2 Carboxile group /Karboksiel-groep (1) 3.3.1 185,4(°C)  (1) - 3.3.2 • Compound B/carboxylic acid has hydrogen bonding (in addition to London forces/Dispersion forces/Induced dipole forces/dipole-dipole forces.). Verbinding B/karboksielsuur het waterstofbindings behalwe Londonkragte/Dispersiekragte/Geïnduseerde dipoolkragte en dipool-dipoolkragte) • Hydrogen bonds are stronger  than London forces/Dispersion forces/Induced dipole forces and dipole-dipole forces. Waterstofbindings is sterker as Londonkragte/Dispersiekragte/ Geïnduseerde dipoolkragte en dipool-dipoolkragte. • More energy will be needed to overcome/break(intermolecular) forces.  Meer energie word benodig om (intermolekulȇre) kragte te oorkom/ te breek. (3) 3.4.1 Organic molecules with the same molecular formula  but different structural formulae.  Organiese verbindings met dieselfde molekulȇre formule maar verskillende struktuurformules. (2) 3.4.2 CHAIN /KETTING (1) 3.4.3 SMALLER THAN /KLEINER AS - STRUCTURE/STRUKTUUR: Compound D are branched/more compact/more spherical/smaller contact area/smaller surface(over which intermolecular forces act.)  Verbinding D is meer vertak/meer kompak/meer series/kleiner kontak area/kleiner oppervlak(waaroor intermolekulȇre kragte werk.) INTERMOLECULAR FORCES/INTERMOLEKULȆRE KRAGTE Weaker/Less strength/Decrease in strength of Van der Waals forces/ London forces/Dispersion forces.  Swakker/Afname in sterkte van Van der Waalskragte/Londonkragte/ Dispersiekragte. 4

Downloaded from hlayiso.com ENERGY/ENERGIE: Less energy needed to overcome/break (intermolecular) forces.  Minder energie benodig om (intermolekulȇre) kragte te oorkom/breek. OR/OF STRUCTURE/STRUKTUUR: Compound C is a straight chain/less compact/less spherical/larger contact area/larger surface(over which intermolecular forces act.)  Verbinding C is ʼn reguitketting/minder kompak/minder sferies/groter kontakarea/groter oppervlak(waaroor intermolekulȇre kragte werk.) INTERMOLECULAR FORCES/INTERMOLEKULȆRE KRAGTE Stronger/More strength/Increase in strength of Van der Waals forces/ London forces/Dispersion forces.  Sterker/Toename in sterkte van Van der Waalskragte/Londonkragte/ Dispersiekragte. ENERGY/ENERGIE More energy needed to overcome/break (intermolecular) forces.  Meer energie word benodig om (intermolekulȇre) kragte te oorkom/breek. (4) [15] QUESTION/VRAAG 4 4.1.1 Substitution /Substitusie (1) 4.1.2 Eliminasie /Dehydration Eliminasie/Dehidrasie/Dehidratering (1) 4.2.1 Hydrogenation  Hidrogenasie/Hidrogenering (1) 4.2.2 Pt /Ni/Pd/Platinum/Nickel/Nikkel/Palladium (1) 4.3 H H H H H H H H H C C C C O H + H-Br → H C C C C Br + H2O  H H H H   H H H H  Notes/Aantekeninge: • Ignore double arrows/Ignoreer dubbelpyle. • Accept/Aanvaar H2O • Any additional reactants and/ or products Enige addisionele reaktanse en/of produkte: Max./Maks. 3/4 • Accept any coefficients that are multiples: Aanvaar koëffisiente wat veelvoude is: • Incorrect balancing/Verkeerde balansering: Max./Maks. 3/4 • Molecular/Condensed formulae Molekulȇre/gekondenseerde formule: Max./Maks. 2/4 Accept/Aanvaar: -OH as condensed/-OH as gekondenseerd (4) 5

Downloaded from hlayiso.com 4.4.1 (Concentrated) sulphuric acid /hydrogen sulphate/H2SO4 Gekonsentreerde swaelsuur/waterstofsulfaat/ H2SO4 (1) 4.4.2 H H H H  C C C C H 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 (2) 4.5.1 • Heat /mild temperature over waterbath. Verhit/matige temperatuur oor ’n waterbad. • Add concentrated sulphuric acid/H2SO4  Voeg gekonsentreerde swawelsuur/waterstofsulfaat)/H2SO4 by. (2) 4.5.2  Marking criteria/Nasienriglyne: O Only functional group  Slegs funksionele groep H C O H Whole structure correct   Hele struktuur korrek 2/2 (2) 4.5.3 Butyl  methanoate / butielmetanoaat (2) [17] QUESTION/VRAAG 5 5.1.1 Use magnesium powder.  Gebruik magnesiumpoeier. (1) 5.1.2 Increase concentration (H2SO4) /Toename in konsentrasie (H2SO4) (1) 5.1.3 DECREASES /VERLAAG (1) 5.1.4 NO EFFECT /GEEN EFFEK (1) 6

Downloaded from hlayiso.com 5.2.1 Surface area  (of Zn)/State of division(of Zn) Oppervlaksarea(van Zn) /Toestand van verdeeldheid(van Zn) (1) 5.2.2 Reaction stops /come to completion/no more hydrogen gas is produced since zinc is used up.  Reaksie stop/kom tot stilstand/geen waterstofgas word geproduseer want sink is opgebruik. (2) 5.2.3 EQUAL TO /GELYK AAN - The same Volume of H2(g) was produced.  Dieselfde volume H2(g) is geproduseer. (2) 5.2.4 (a) Average rate/Gemiddelde tempo = ΔV/Δt = (0,06 - 0) /(30 - 0)  = 2 x 10-3(mol.dm-3.s-1) or/of 0,002 (3) (b) n = cV = 0,4 x 100/1000  = 0,04 mol  (3) (c) Marking criteria/Nasienriglyne: • Use 24,3 dm3.mol-1 substituted in the correct formula. Gebruik 24,3 dm3.mol-1 vervang in die korrekte formule. • Calculate n(HCl) reacted using the mol ratio 1 : 2.  Bereken n(HCl)gereageer deur molverhouding 1 : 2 te gebruik. • Calculate n(HCl) reacted  Bereken n(HCl)gereageer • Use 36,5 g.mol-1 substitute in correct formule.  Gebruik 36,5 g.mol-1 vervang in die korrekte formule. • Finale antwoord/Final answer. (1,28–1,31 g) POSITIVE MARKING from QUESTION 5.2.4 b + POSITIEWE NASIEN vanaf VRAAG 5.2.4 b n(H2)produced/berei = V/Vm= 0,06/24,3 = 2,47 x 10-3mol (0,002) n( HCℓ)lreacted/gereageer = 2 x 2,47 x 10-3 Ratio/Verhouding = 4,94 x 10 -3 mol (0,004) n(HCℓ )remaining/oorgebly = ninitial/begin - nproduced/berei = 0,04 – 4,94 x10-3 = 0,03506 mol (0,036) m = nM = 0,03506 x 36,5= 1,28 g Range/Gebied (1,28–1,314 g) (5) 5.2.5 The minimum energy required to start a chemical reaction.  Die minimum energie benodig om ʼn reaksie te begin. (2 or/of 0) (2) 7

Downloaded from hlayiso.com 5.2.6 Experiment/Eksperiment III  (1) 5.2.7 • A catalyst  provides an alternative pathway of lower activation energy(EA).  ʼn Katalisator verskaf ʼn alternatiewe pad van laer aktiveringsenergie. • More particles will have sufficient/enough kinetic energy(Ek) to react.  /More particles with Ek ≥ EA. Meer deeltjies het voldoende(genoegsame) kinetiese energie(Ek) om te reageer./Meer deeltjies het Ek ≥ EA. • More effective collisions per unit time/second.  Meer effektiewe botsings per eenheidstyd/sekonde. OR/OF Rate/frequency of effective collisions increases. Tempo/frekwensie van effektiewe botsings neem toe. (4) [27] QUESTION/VRAAG 6 6.1 Stage at which the rate of forward reaction equals the rate of reverse.  Die toestand/stadium in ʼn chemiese reaksie wanneer die tempo van die voorwaartse reaksie gelyk is aan die tempo van die terugwaartse reaksie. OR/OF The stage where the concentrations/quantities of reactants and products remain constant. Die toestand wanneer die konsentrasies/hoeveelhede van reaktanse en produkte konstant bly. (2 or/of 0) (2) 6.2 Closed system /Geslote sisteem Reversible reaction /Omkeerbare reaksie. (2) 6.3.1 NO EFFECT /GEEN EFFEK (1) 6.3.2 INCREASES /TOENEEM (1) 6.4.1 REVERSE /TERUGWAARTSE (1) 6.4.2 Increase in pressure  /Decrease volume; Addition of a catalyst.  Verhoog druk/Afname in volume; Byvoeging van ʼn katalisator. (2) 6.5.1 LOW (yield) /LAE (opbrengs) Kc is low. /Kc is laag. (2) 8

Downloaded from hlayiso.com 6.5.2 Marking Criteria/Nasienriglyne: • Divide by 34 to calculate n(H2S)equilibrium.  Verdeel deur 34 om n(H2S)ewewig te bereken. • Use mole ratio H2:H2S/Gebruik mol verhouding H2:H2S  (1 : 1) • Divide n(H2S) equilibrium by V./Verdeel n(H2S) ewewig deur V.  • Correct Kc expression/Korrekte Kc uitdrukking.  • Substitution of Kc -value./Vervanging van Kc waarde.  • Substitution into Kc expression/Substitueer in Kc uitdrukking.  • Calculate /Bereken n(H2)equilibrium/ewewig  • Final answer/Finale antwoord n(H2) initial/begin = 2,45 mol  OPTION/OPSIE 1 n(H2S)equilibrium/ewewig = m/M = 17/34 = 0,5 mol H2 S H2S ninitial/begin (mol) 0 ratio/ Δn (mol) 0,5 0,5 0,5 verhouding  nequilibrium/ewewig(mol) 0,5 cequilibrium/ewewig (mol.dm-3) nequilibrium/ewewig/V 0,5/V ÷V  Kc = [H2S]/[H2]  2,56 x 10-1  = (0,5/V)/(n(H2)equilibrium/ewewig/V)  n(H2)equilibrium/ewewig = 1,95 mol  n(H2)initial/begin = 0,5 + 1,95 = 2.45 mol  (8) 6.5.3 POSITIVE MARKING from QUESTION 6.5.2 + POSITIEWE NASIEN vanaf VRAAG 6.5.2 90/100 ni(S)  = ni(S) – 0,5  ni(S) = 5 mol  (3) 6.5.4 Graph/Grafiek Q - • As temperature increases, Kc decreases.  Indien die temperatuur toeneem, neem Kc af. • [H2S] decreases/[H2] increases. [H2S] neem af/ [H2] verhoog. • Reverse reaction is favoured by an increase in temperature.  Terugwaartse reaksie word bevoordeel deur ʼn verhoging in temperatuur. (4) [26] 9

Downloaded from hlayiso.com QUESTION/VRAAG 7 7.1.1 Hydrolysis /Hidrolise (1) 7.1.2 Transfer of proton(H+) occurs./ CO32- gains a proton / H2O loses a proton. Oordrag van proton(H+) vind plaas/CO32- ontvang ʼn proton/H2O verloor ʼn proton(H+). (1) 7.1.3 OH- (1) 7.1.4 Kb < 1 x 10 -14 (1) 7.1.5 Substance that can act either as an acid or base./  ʼn Stof wat as beide suur of basis kan optree. (2) 7.1.6 H2CO3  (1) 7.1.7 CO3-2  (1) 7.2.1 An acid that donates TWO protons/H+/H3O+-ions.  ʼn Suur wat TWEE protone/H+/H3O+-ione vrystel. (2) 7.2.2 pH = - log [H3O+] 1,3= - log [H3O+] [H3O+]= 10-1,3 [OH-][H3O+] = 1 x 10-14 [OH-] x 10-1,3 =1 x 10-14 [OH-] = 10-12,7 mol.dm-3 = 1,995 x 10-13 mol.dm-3 (4) 7.3.1 POSITIVE MARKING FROM Q 7.2.2/POSITIEWE NASIEN VANAF V7.2.2 OPTION /OPSIE 1 + [H3O+] = 10-1,3 mol.dm-3 [Acid] = ½ x10-1,3  = 0,0251 mol.dm-3 Dilution c1V1= c2V2 0,0251(8) = c2 x 100 c2(dilute) = 2,008 x 10-3 mol.dm-3 n(acid reacting) = cV = 2,008 x 10-3 x 25/1000 = 5,02 x 10-5 mol n(base reacting) = 2 x 5,02 x 10-5 = 1,004 x 10-4 mol c(base) = n/V = 1,004 x 10-4/14,2 x 10-3  = 7,07 x 10-3 mol.dm-3 (6) 10

Downloaded from hlayiso.com OPTION/OPSIE 2 [H3O+] = 10-1,3 mol.dm-3 [Acid] = ½ x10-1,3  = 0,0251 mol.dm-3 c1V1 = c2V2 (0,0251)(8) = c2 x 100 c2 = 2,008 x 10-3 mol.dm-3 caVa = na cbVb nb 2,008 x 10-3 ( 25)  = 1 cb x 14,2  2 cb = 7,07 x 10-3 mol.dm-3  Range/Gebied ( 7,04 x 10-3 to/tot 7,07 x 10-3 mol.dm-3) 7.3.2 B Titration of a strong base and a strong acid  (solution at end point neutral.) - Titrasie van ʼn sterk basis en ʼn sterk suur (oplossing is neutraal by eindpunt.) (2) [22] TOTAL/TOTAAL: 150 11