Physical Sciences Grade 12 Free StateNovember 2016 Memo

Downloaded from hlayiso.com PREPARATORY EXAMINATION VOORBEREIDENDE EKSAMEN GRADE/GRAAD 12 PHYSICAL SCIENCES: CHEMISTRY (P2) FISIESE WETENSKAPPE: CHEMIE (V2) SEPTEMBER 2016 MARKS/PUNTE: 150 MEMORANDUM This memorandum consists of 13 pages. Hierdie memorandum bestaan uit 13 bladsye. Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 2 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum QUESTION 1/VRAAG 1 1.1 B  (2) 1.2 B  (2) 1.3 D  (2) 1.4 B  (2) 1.5 D  (2) 1.6 B  (2) 1.7 B  (2) 1.8 D  (2) 1.9 C  (2) 1.10 C  (2) [20] QUESTION 2/VRAAG 2 2.1.1 E  (1) 2.1.2 C  (1) 2.1.3 A  (1) 2.1.4 B  (1) 2.2.1 (2)  2.2.2 Ethanoic acid/etanoësuur  and/en ethanol/etanol (2) 2.3.1 Butan-2-one/Butanone/Butan-2-oon/Butanoon  (2) 2.3.2 1,2-dibromo butane/Butaan  (2) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 3 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum O II 2.4 CH 3 CH 2 COCH 3 /C 2 H 5 CCH 3  (2) 2.5.1  H H C H H H H H C C C C H H H H H (2) Marking criteria/Nasienriglyne: • Whole structure correct/Hele struktuur korrek: 2 /2 • Only functional group correct/single bonds between carbon atoms: ½ Slegs funksionele groep korrek/enkel bindings tussen koolstofatome OR/OF H H H H H H C C C C C H H H H H H Notes/Aantekeninge: • If correct but hydrogens omitted/Indien korrek maar waterstowwwe weggelaat Max./Maks ½ • Condensed formulae or semi structural formula/ Gekondenseerde of semistrukturele formule Max./Maks. ½ 0 • Molecular formula/Molekulêre formule /2 2.5.2 Marking criteria/Nasienriglyne: • Whole structure correct/Hele struktuur korrek: 2 /2 • Only functional group correct/Slegs funksionele groep korrek: ½  (2) [18] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 4 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum QUESTION 3/VRAAG 3 3.1.1 Chain length/Molecular mass/Number of carbon atoms  Kettinglengte/Molekulêre massa/Aantal koolstofatome (1) 3.1.2 Boiling point/Kookpunt  (1) 3.1.3 Criteria for investigative question/Riglyne vir ondersoekende vraag: The dependent and independent variables are stated.  Die afhanklike en onafhanklike veranderlikes is genoem. Gives the relationship between the independent and dependent variables./Vra 'n vraag oor die verwantskap tussen die onafhanklike  en afhanklike veranderlikes. Examples/Voorbeelde: • What is the relationship between chain length/molecular mass/number of carbon atoms and the boiling points of the organic compounds? Wat is die verwantskap tussen kettinglengte/molekulêre massa/aantal koolstofatome en die kookpunt van die organiese verbindings? (2) 3.2 Decreases/Neem af  • Structure/Strukture: The branching increases/surface area decreases.  Die vertakking neem toe/oppervlakte neem af • Intermolecular forces/Intermolekulêre kragte: Decrease in strength of intermolecular forces/or less intermolecular forces/Van der Waals forces/dispersion forces/London forces.  Afname in sterkte van intermolekulêre kragte/of minder intermolekulêre kragte/Van der Waalskragte/dispersiekragte/Londonkragte • Energy/Energie: Less energy needed to overcome or break intermolecular forces/Van der. Waals forces/dispersion forces /London forces.  Minder kragte nodig om intermolekulêre kragte te oorkom/Van der Waalskragte/dispersiekragte/Londonkragte (4) 3.3.1 Alkanes/Alkane (1) 3.3.2 2,2-dimethyl propane/2,2-dimetielpropaan (2) Marking criteria/Nasienriglyne: • Correct stem i.e. propane./Korrekte stam d.i. pentaan.  • All substituents correctly identified and correctly numbered/Alle substituente korrek geïdentifiseer en korrek genommer  [11] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 5 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum QUESTION 4/VRAAG 4 4.1.1 Substitution/halogenation/Substitusie/halogenering  (1) 4.1.2 Elimination/dehydrohalogenation/Eliminasie/dehidrohalogenering  (1) 4.1.3 Addition/Hydrogenation/Addisie/Hidrogenering/Hidrogenasie (1) 4.2 4.2.1 2-chloropropane/2-chloropropaan/2-chloorpropaan (2) 4.2.2    H Cl H H H H C C C H C C C H + HCl H H H H H H (4) Notes/Aantekeninge: • Ignore/Ignoreer ⇌ • Accept HCℓ if condensed/Aanvaar HCℓ indien gekondenseer • Any additional reactants and/or products/Enige addisionele reaktanse en/of ander produkte Max./Maks. 3 4 • Accept coefficients that are multiples/Aanvaar koëffisiënte wat veelvoude is • Molecular/condensed formulae/Molekulêre/gekondenseerde formules Max./Maks. 3 4 4.3.1 A compound in which a hydroxyl group is attached to a carbon atom which has two other carbon atoms attached to it.  'n Verbinding waarin 'n hidroksielgroep aan 'n koolstofatoom verbind is, waaraan twee ander koolstofatome verbind is. (2) 4.3.2 Propan-2-ol/Propaan-2-ol OR/OF 2-propanol/2-propanol (2) [13] QUESTION 5/VRAAG 5 5.1 A reaction which does not need (activation) energy to start.  'n Reaksie wat nie (aktiverings-) energie benodig om te begin nie. (2) 5.2 Hydrochloric acid/HCℓ/Soutsuur/ HCℓ  (1) 5.3.1 Decreases/Neem af  (1) 5.3.2 Increases/Neem toe  (1) 5.3.3 Increases/Neem toe (1) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 6 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum 5.3.4 • At higher temperature more molecules have enough /sufficient kinetic energy/more molecules have kinetic energy greater than activation energy. Teen 'n hoër temperatuur het meer molekule genoeg kinetiese energie/ meer molekule het kenetiese energie goter as die aktiveringsenergie • More effective collisions per unit time/second.  Meer effektiewe botsings per eenheid tyd/sekonde (3) [9] QUESTION 6/ VRAAG 6 6.1 Haber (process)/Haberproses (1) 6.2 Iron/ Fe/Yster/ Fe  (1) 6.3 • The forward and reverse reactions take place simultaneously at the same rate. Die voorwaartse en terugwaartse reaksies vind gelyktydig teen dieselfde tempo plaas. • The amount of energy given off by exothermic reaction is taken up by the endothermic reaction.  Die hoeveelheid energie wat deur die eksotermiese reaksie vrygestel word, word deur die endotermiese reaksie opgeneem. (2) 6.4 CALCULATIONS USING NUMBER OF MOLES/ BEREKENINGE WAT GETAL MOL GEBRUIK Mark allocation/Puntetoekenning: • Correct Kc expression (formulae in square brackets)  Korrekte Kc –uitdrukking (formules in vierkanthakies) • Substitution of concentrations into KC expression  Vervanging van konsentrasies in Kc-waardes • Substitution of Kc 0,1/Vervanging van Kc 0,1 • Equilibrium/Ewewig: n(N2)  n(NH3)  • Equilibrium/Ewewig: n(NH3) = n : Change/Verandering  • USING ratio: N2 : 3H2 : 2NH3 = 1 : 3 : 2  GEBRUIK verhouding: N2 : 3H2 : 2NH3 = 1 : 3 : 2 • Initial mole of N2 = Equilibrium + Change  Aanvangsmol van N2 = Ewewig + Verandering m • Substitution of n & M into formula n (N 2 ) =  M m Vervanging van n & M in formule n (N 2 ) = M • Final answer: 0,58g/Finale antwoord Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 7 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum K = [NH 3 ] 2  C [ N 2 ][ H 2 ]3  0,1 = (2,7 x10 )  -3 2 (N 2 )(1,221 x 10 -1 ) 3 [N 2 ] = 4 x10 -2 mol.dm -3 N2 H2 NH 3 Initial quantity (mol) 0 Aanvangshoeveelheid (mol) 2,07 x 10-2 2,936 x 10-3 Change (mol) 6,75 x 10-4 ratio  Verandering (mol) 2,025 x 10-3 1,35 x 10-3  Quantity at equilibrium (mol) n = cv 0,02  6,105 x 10-2 1,35 x 10-3  Hoeveelheid by ewewig (mol) Equilibrium concentration (mol∙dm-3) 2,7 x 10-3 Ewewigskonsentrasie (mol∙dm-3) 4 x 10 -2 1,221 x 10 -1 Mass/massa (N 2 ) m = nM  = (2,07 x 10-2) x (28) = 5,79 x 10-1g/ 0,58g  OR/OF 2,07 x 10-2 m = 5,79 x 10-1g/0,58g (10) 6.5 A decrease in temperature will increase the yield , but the reaction will be slow  and the profit margins will be low.  'n Afname in temperatuur sal tot 'n toename in opbrengs lei, maar die reaksie sal stadig wees en die winsgrens laag. OR/OF Increase in temperature favours the reverse reaction , but reaction takes place much quicker  and the process is less expensive . 'n Toename in temperatuur is voordelig vir die terugwaartse reaksie, maar reaksies sal baie vinniger wees en die proses goedkoper. (3) [17] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 8 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum QUESTION 7/VRAAG 7 7.1.1 An acid that dissociates/ionises completely in water  'n Suur wat heeltemal in water ioniseer/dissosieer (2) 7.1.2 HCℓ(aq) + H 2 O(ℓ)  → H 3 O+(aq) + Cℓ-(aq)   balancing/balansering OR/OF HCℓ + H 2 O  → H 3 O + Cℓ  + -  balancing/balansering (3) 7.1.3 Acid pH below (<)7 /Suur pH onder (<)7 (2) 7.1.4 pH = -log[H 3 O+] OR/OF pH = -log[H+] 4 = -log[H 3 0+] [H 3 0+] = 1 x 10-4 mol.dm-3 (3) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 9 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum 7.1.5 POSITIVE MARKING FROM QUESTION 7.1.4/POSITIEWE NASIEN VANAF VRAAG 7.1.4 Marking criteria/Nasienriglyne: • Final/Finale n(HCℓ): Multiplying/ Vermenigvuldig1 x 10-4mol.dm-3 by/ met 0,17 dm3  • Initial/Aanvanklike n(HCℓ):Multiplying/Vermenigvuldig 0,03 mol.dm-3 by/met 0,15 dm3  • n(HCℓ reacted/reageer) = initial/ Aanvanklike – final/ finale . • Use mol ratio of acid:base/Molverhouding suur:basis= 1 : 1.  n • Substitute/Vervang: n(NaOH) in c =  V • Final answer /Finale antwoord: 0,22 mol.dm-3  n(HCℓ in excess/ in oormaat): n c= V n(HCℓ) = (1 x 104)(0,17)  = 1,7 x 10-5 mol n(HCℓ initial/ aanvanklik): n c= V n(HCℓ) = (0,03)(0,15)  = 4,5 x 10-3 mol n(HCℓ reacted/reageer) = 4,5 x 10-3 - 1,7 x 10-5  = 4,48 x 10-3 mol Ratio/Verhouding n(HCℓ) = n(NaOH) = 4,48 x 10-3  c(NaOH) initial/ aanvanklik : c = 4,483 x 10-3/ 2 x 10-2  = 0,22 mol.dm-3  (6) [22] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 10 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum 7.2 Marking criteria/Nasienriglyne: • Divide volume by/Deel volume deur: 22,4  • Use ratio/Gebruik verhouding: n(CO 2 ) = n(CaCO 3 ) = 1:1  m • Substitute/Vervang 100 in n = . M • Mass/Massa (4g – 4,46g)  • Divide by/Deel deur 5 x 100  • Final answer/Finale antwoord: 80% to 90%  V n (CO 2 ) = Vm 1,06 =  22,4 = 0,04 mol (0,0446 mol) n(CaCO 3 ) = n(CO 2 ) = 0,04 mol  (0, 0446 mol) m n(CaCO3 ) = M m 0,04 = 100  ∴ m = 4 g (4,46 g)  % CaCO 3 = 80 %  (6) (Accept range/Anvaar variasie: 80% – 90%) [22] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 11 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum QUESTION 8/VRAAG 8 8.1 To complete the circuit/to maintain electrical neutrality  Om die stroombaan te voltooi/om elektriese neutraliteit te handhaaf (1) 8.2 Ni  (1) 8.3 (5) E cθ e= lEl rθ e d u Ec oθ t ix o i dn  − Notes/Aantekeninge: Accept any other correct formula from the data 1,07  = E°x – (-0,27)  sheet. E°x = 0,8 (V)  Aanvaar enige ander korrekte formule vanaf gegewensblad. X is silver/ Ag.  Any other formula using unconventional Option 2/ Opsie 2 θ θ θ abbreviations, e.g. Ec e =l l EO A ER Afollowed by − Ni→ Ni2+ + 2e- E° = 0,27(V)  correct substitutions: 5 4 X+ + e- → X E° = 0,8 (V)  Enige ander formule wat onkonvensionele afkortings E° = 1,07 V  θ θ θ θ gebruik bv. E s e l= E O M E R M gevolg deur korrekte Thus/Dus: E reduction = 0,8 (V)  − 4 X is silver/ Ag.  vervangings: 5 8.4 Ni + 2Ag+  → Ni+ + 2Ag   balancing/balansering OR/OF Ni + 2X+  → Ni+ + 2X+   balancing/balansering (3) 8.5.1 Nickel ions/ Ni2+/Nikkelione/ Ni2+ (1) 8.5.2 Zn → Zn2+ + 2e-  (2) Marking guidelines/Nasienriglyne: 1 0 • Zn ⇌ Zn2+ + 2e- 2 Zn2+ + 2e- ⇌ Zn 2 2 0 Zn + 2e ← Zn 2+ - 2 Zn 2+ + 2e → Zn - 2 8.5.3 Zn(s) | Zn2+(aq) (1 mol.dm-3) || Ni2+(aq) (1 mol.dm-3) | Ni(s)  OR/OF 2+ 2+ Zn(s) | Zn (aq)  || Ni (aq) | Ni(s)  OR/OF 2+ 2+ Zn | Zn  || Ni | Ni  (3) [16] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 12 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum QUESTION 9/VRAAG 9 9.1 Electrical (energy) to chemical (energy)  Elektriese (energie) na chemiese (energie) (1) 9.2 Bauxite  (1) 9.3 Decreases melting point of aluminium oxide Laat smeltpunt van aluminiumoksied afneem (1) 9.4 C(s) + O 2 (g) → CO 2 (g)   balancing/balansering (2) 9.5 Aℓ3+ + 3e- → Aℓ  (1) 9.6 ANY TWO • The cell produces red mud waste, which can result in the alkali seeping through the soil and contaminating water supplies.  • Consumes large quantities of energy, which leads to load-shedding/ increased emission of green house gases.  • Carbon dioxide from the burning of the anodes contributes to the (enhanced) greenhouse effect (air pollution/global warming).  • Carbon dioxide is poisonous.  • Fluorine (and fluorine compounds) lost from the cryolite during the electrolysis process is poisonous.  • Loss of landscape due to the size of the chemical plant needed.  • Pollution caused by power generation (for electrolytic process) using coal-fired plants leads to acid rain/enhanced (greenhouse effect).  • Noise pollution ENIGE TWEE • Die sel produseer rooi modderafval wat kan lei tot alkali wat deur die grond sypel en die watertoevoer besoedel. • Groot hoeveelhede energie word gebruik, wat tot beurtkrag aanleiding kan gee/die vrystelling van kweekhuisgasse laat toeneem. • Koolstofdioksied vrygestel deur die brand van anodes dra by tot die kweekhuiseffek (lugbesoedeling/aardverwarming). • Koolstofdioksied is giftig. • Fluoor (en fluoor verbindings) vrygestel deur die krioliet tydens die elektroliseproses is giftig. • Landskap word vernietig deur groot chemiese aanleg wat benodig word. • Besoedeling veroorsaak deur kragopwekking (vir elektrolitiese proses) deur die gebruik van steenkoolaanlegte lei tot suurreën/kweekhuiseffek neem toe. • Geraasbesoedeling (2) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief

Downloaded from hlayiso.com Physical Sciences P2/Fisiese Wetenskappe P2 13 FS/VS/September 2016 Grade/Graad 12 Prep.Exam./Voorb.Eksam Memorandum 9.7 The extraction cell uses too much electrical energy, recycling saves energy.  Die ontrekkingselle gebruik te veel elektriese energie, herwinning spaar energie Clean environment from littering. Voorkom omgewingsbesoedeling. (2) [10] QUESTION 10/VRAAG 10 10.1.1 Sulphur dioxide/ SO 2 /Swaweldioksied/ SO 2  (1) 10.1.2 Catalytic oxidation of SO 2 /Katalitiese oksidasie van SO 2  (1) 10.1.3 Vanadium pentoxide (V 2 O 5 )/Vanadium pentoksied (V 2 O 5 ) (1) 10.1.4 H 2 S 2 O 7  (2) 10.1.5 NH 3  + H 2 SO 4  → (NH 4 ) 2 SO 4  balancing/balansering (4) 10.2 ANY ONE /ENIGE EEN • Fertilisers in water leads to eutrophication which can result in less drinking water/starvation due to dying of fish/less water recreation areas. Kunsmis in water lei tot eutrofikasie wat beteken dat minder drinkwater beskikbaar sal wees/hongersnood a.g.v. vrektes van die vispopulasie/minder waterbronne vir ontspanning. • Fertilisers in water leads to excess of nitrates in water resulting in blue baby syndrome/cancer. / Kunsmis in water lei tot oormaat nitraat in water wat aanleiding gee tot bloubabasindroom/kanker. (2) 10.3.1 Nitrogen/Stikstof  (1) 10.3.2 Potassium/Kalium  (1) 10.4 Phosphorus/Fosfor  (1) [14] GRAND TOTAL/GROOTTOTAAL: 150 Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief